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KSH(1)				 User commands				KSH(1)

       ksh - Public domain Korn	shell

       ksh [+-abCefhikmnprsuvxX] [+-o option] [	[ -c command-string [command-
       name] | -s | file ] [argument ...] ]

       ksh is a	command	interpreter that is intended for both interactive  and
       shell  script  use.   Its  command  language is a superset of the sh(1)
       shell language.

   Shell Startup
       The following options can be specified only on the command line:

       -c command-string
	      the shell	executes the command(s)	contained in command-string

       -i     interactive mode -- see below

       -l     login shell -- see below interactive mode	-- see below

       -s     the shell	reads commands from  standard  input;  all  non-option
	      arguments	are positional parameters

       -r     restricted mode -- see below

       In  addition  to	 the  above, the options described in the set built-in
       command can also	be used	on the command line.

       If neither the -c nor the -s options  are  specified,  the  first  non-
       option  argument	 specifies the name of a file the shell	reads commands
       from; if	there are no non-option	arguments, the	shell  reads  commands
       from  standard input.  The name of the shell (i.e., the contents	of the
       $0) parameter is	determined as follows: if the -c option	 is  used  and
       there is	a non-option argument, it is used as the name; if commands are
       being read from a file, the file	is used	as  the	 name;	otherwise  the
       name the	shell was called with (i.e., argv[0]) is used.

       A  shell	 is  interactive  if the -i option is used or if both standard
       input and standard error	are attached to	a tty.	An  interactive	 shell
       has  job	control	enabled	(if available),	ignores	the INT, QUIT and TERM
       signals,	and prints prompts before  reading  input  (see	 PS1  and  PS2
       parameters).   For non-interactive shells, the trackall option is on by
       default (see set	command	below).

       A shell is restricted if	the -r option is used or if either  the	 base-
       name of the name	the shell is invoked with or the SHELL parameter match
       the pattern *r*sh (e.g.,	 rsh,  rksh,  rpdksh,  etc.).	The  following
       restrictions come into effect after the shell processes any profile and
       $ENV files:
	 o    the cd command is	disabled
	 o    the SHELL, ENV and PATH parameters can't be changed
	 o    command names can't be specified with absolute or	relative paths
	 o    the -p option of the command built-in can't be used
	 o    redirections  that  create files can't be	used (i.e., >, >|, >>,

       A shell is privileged if	the -p option is used or if the	 real  user-id
       or  group-id  does  not	match  the  effective user-id or group-id (see
       getuid(2), getgid(2)).  A privileged shell does not process $HOME/.pro-
       file nor	the ENV	parameter (see below), instead the file	/etc/suid_pro-
       file is processed.  Clearing the	privileged option causes the shell  to
       set its effective user-id (group-id) to its real	user-id	(group-id).

       If  the	basename  of the name the shell	is called with (i.e., argv[0])
       starts with - or	if the -l option is used, the shell is assumed to be a
       login  shell and	the shell reads	and executes the contents of /etc/pro-
       file and	$HOME/.profile if they exist and are readable.

       If the ENV parameter is set when	the shell starts (or, in the  case  of
       login shells, after any profiles	are processed),	its value is subjected
       to parameter,  command,	arithmetic  and	 tilde	substitution  and  the
       resulting  file (if any)	is read	and executed.  If ENV parameter	is not
       set (and	not null) and pdksh was	compiled with  the  DEFAULT_ENV	 macro
       defined,	the file named in that macro is	included (after	the above men-
       tioned substitutions have been performed).

       The exit	status of the shell is 127 if the command  file	 specified  on
       the  command  line  could  not be opened, or non-zero if	a fatal	syntax
       error occurred during the execution of a	script.	  In  the  absence  of
       fatal  errors, the exit status is that of the last command executed, or
       zero, if	no command is executed.

   Command Syntax
       The shell begins	parsing	its input by breaking it into  words.	Words,
       which  are  sequences  of  characters, are delimited by unquoted	white-
       space characters	(space,	tab and	newline) or meta-characters (<,	>,  |,
       ;,  &,  (  and  )).   Aside  from delimiting words, spaces and tabs are
       ignored,	while newlines usually delimit commands.  The  meta-characters
       are  used  in building the following tokens: <, <&, <<, >, >&, >>, etc.
       are used	to specify redirections	(see Input/Output Redirection  below);
       |  is  used to create pipelines;	|& is used to create co-processes (see
       Co-Processes below); ; is used to separate commands; & is used to  cre-
       ate  asynchronous  pipelines; &&	and || are used	to specify conditional
       execution; ;; is	used in	case statements; (( .. )) are used  in	arith-
       metic expressions; and lastly, (	.. ) are used to create	subshells.

       White-space  and	meta-characters	can be quoted individually using back-
       slash (\), or in	groups using double (")	or single  (')	quotes.	  Note
       that  the  following characters are also	treated	specially by the shell
       and must	be quoted if they are to represent themselves: \, ", ',	#,  $,
       `,  ~,  {,  }, *, ? and [.  The first three of these are	the above men-
       tioned quoting characters (see Quoting below); #, if used at the	begin-
       ning  of	 a  word, introduces a comment -- everything after the # up to
       the nearest newline is ignored; $ is used to introduce parameter,  com-
       mand  and  arithmetic  substitutions (see Substitution below); `	intro-
       duces an	old-style command substitution	(see  Substitution  below);  ~
       begins  a  directory  expansion	(see  Tilde  Expansion below); { and }
       delimit csh(1) style alternations (see  Brace  Expansion	 below);  and,
       finally,	 *,  ?	and  [ are used	in file	name generation	(see File Name
       Patterns	below).

       As words	and tokens are parsed, the shell  builds  commands,  of	 which
       there are two basic types: simple-commands, typically programs that are
       executed, and compound-commands,	such as	for and	if statements,	group-
       ing constructs and function definitions.

       A  simple-command consists of some combination of parameter assignments
       (see Parameters below),	input/output  redirections  (see  Input/Output
       Redirections  below),  and  command words; the only restriction is that
       parameter assignments come  before  any	command	 words.	  The  command
       words,  if any, define the command that is to be	executed and its argu-
       ments.  The command may be a shell built-in command, a function	or  an
       external	 command,  i.e.,  a  separate  executable file that is located
       using the PATH parameter	(see Command Execution below).	Note that  all
       command	constructs have	an exit	status:	for external commands, this is
       related to the status returned by wait(2) (if the command could not  be
       found,  the  exit  status is 127, if it could not be executed, the exit
       status is 126); the exit	status of other	command	 constructs  (built-in
       commands, functions, compound-commands, pipelines, lists, etc.) are all
       well defined and	are described where the	construct is  described.   The
       exit  status  of	 a command consisting only of parameter	assignments is
       that of the last	command	substitution performed	during	the  parameter
       assignment or zero if there were	no command substitutions.

       Commands	 can  be chained together using	the | token to form pipelines,
       in which	the standard output of each command but	the last is piped (see
       pipe(2))	to the standard	input of the following command.	 The exit sta-
       tus of a	pipeline is that of its	last command.  A pipeline may be  pre-
       fixed  by the ! reserved	word which causes the exit status of the pipe-
       line to be logically complemented: if the original  status  was	0  the
       complemented  status  will  be 1, and if	the original status was	not 0,
       then the	complemented status will be 0.

       Lists of	commands can be	created	by separating pipelines	by any of  the
       following  tokens:  &&,	||, &, |& and ;.  The first two	are for	condi-
       tional execution: cmd1 && cmd2 executes cmd2 only if the	exit status of
       cmd1  is	 zero; || is the opposite -- cmd2 is executed only if the exit
       status of cmd1 is non-zero.  && and || have equal precedence  which  is
       higher than that	of &, |& and ;,	which also have	equal precedence.  The
       & token causes the preceding command  to	 be  executed  asynchronously,
       that is,	the shell starts the command, but does not wait	for it to com-
       plete (the shell	does keep track	of the status of asynchronous commands
       --  see	Job  Control  below).  When an asynchronous command is started
       when job	control	is disabled (i.e., in most scripts),  the  command  is
       started	with  signals  INT  and	QUIT ignored and with input redirected
       from /dev/null (however,	redirections  specified	 in  the  asynchronous
       command have precedence).  The |& operator starts a co-process which is
       special kind of asynchronous process (see  Co-Processes	below).	  Note
       that  a	command	 must  follow the && and || operators, while a command
       need not	follow &, |& and ;.  The exit status of	a list is that of  the
       last  command  executed,	 with the exception of asynchronous lists, for
       which the exit status is	0.

       Compound	commands are created using the	following  reserved  words  --
       these  words  are  only recognized if they are unquoted and if they are
       used as the first word of a command (i.e., they can't  be  preceded  by
       parameter assignments or	redirections):

			 case	else   function	  then	  !
			 do	esac   if	  time	  [[
			 done	fi     in	  until	  {
			 elif	for    select	  while	  }
       Note: Some shells (but not this one) execute control structure commands
       in a subshell when one or more of  their	 file  descriptors  are	 redi-
       rected,	so any environment changes inside them may fail.  To be	porta-
       ble, the	exec  statement	 should	 be  used  instead  to	redirect  file
       descriptors before the control structure.

       In  the following compound command descriptions,	command	lists (denoted
       as list)	that are followed by reserved words  must  end	with  a	 semi-
       colon, a	newline	or a (syntactically correct) reserved word.  For exam-
	      {	echo foo; echo bar; }
	      {	echo foo; echo bar<newline>}
	      {	{ echo foo; echo bar; }	}
       are all valid, but
	      {	echo foo; echo bar }
       is not.

       ( list )
	      Execute list in a	subshell.  There is no implicit	 way  to  pass
	      environment changes from a subshell back to its parent.

       { list }
	      Compound	construct;  list  is  executed,	but not	in a subshell.
	      Note that	{ and }	are reserved words, not	meta-characters.

       case word in [ [(] pattern [| pattern] ... ) list ;; ] ... esac
	      The case statement attempts to match word	against	the  specified
	      patterns;	 the  list  associated	with  the  first  successfully
	      matched pattern is executed.  Patterns used in  case  statements
	      are  the	same  as those used for	file name patterns except that
	      the restrictions regarding . and / are dropped.  Note  that  any
	      unquoted space before and	after a	pattern	is stripped; any space
	      with a pattern must be quoted.  Both the word and	 the  patterns
	      are  subject  to parameter, command, and arithmetic substitution
	      as well as tilde substitution.  For historical reasons, open and
	      close braces may be used instead of in and esac (e.g., case $foo
	      {	*) echo	bar; }).  The exit status of a case statement is  that
	      of the executed list; if no list is executed, the	exit status is

       for name	[ in word ... term ] do	list done
	      where term is either a newline or	a ;.  For  each	 word  in  the
	      specified	 word  list, the parameter name	is set to the word and
	      list is executed.	 If in is not used to specify a	word list, the
	      positional  parameters ("$1", "$2", etc.)	are used instead.  For
	      historical reasons, open and close braces	may be used instead of
	      do  and  done (e.g., for i; { echo $i; }).  The exit status of a
	      for statement is the last	exit status of list; if	list is	 never
	      executed,	the exit status	is zero.

       if list then list [elif list then list] ... [else list] fi
	      If the exit status of the	first list is zero, the	second list is
	      executed;	otherwise the list following the elif, if any, is exe-
	      cuted with similar consequences.	If all the lists following the
	      if and elifs fail	(i.e., exit with non-zero  status),  the  list
	      following	the else is executed.  The exit	status of an if	state-
	      ment is that of non-conditional list that	 is  executed;	if  no
	      non-conditional list is executed,	the exit status	is zero.

       select name [ in	word ... term ]	do list	done
	      where  term  is  either  a newline or a ;.  The select statement
	      provides an automatic method of presenting the user with a  menu
	      and  selecting  from  it.	  An  enumerated list of the specified
	      words is printed on standard error, followed by a	 prompt	 (PS3,
	      normally	`#?  ').  A number corresponding to one	of the enumer-
	      ated words is then read from standard input, name	is set to  the
	      selected word (or	is unset if the	selection is not valid), REPLY
	      is set to	what was read (leading/trailing	 space	is  stripped),
	      and  list	 is executed.  If a blank line (i.e., zero or more IFS
	      characters) is entered, the menu is re-printed without executing
	      list.   When  list  completes, the enumerated list is printed if
	      REPLY is null, the prompt	is printed and so on.  This process is
	      continues	until an end-of-file is	read, an interrupt is received
	      or a break statement is executed inside the loop.	  If  in  word
	      ...  is omitted, the positional parameters are used (i.e., "$1",
	      "$2", etc.).  For	historical reasons, open and close braces  may
	      be  used	instead	of do and done (e.g., select i;	{ echo $i; }).
	      The exit status of a select statement is zero if a break	state-
	      ment is used to exit the loop, non-zero otherwise.

       until list do list done
	      This  works  like	 while,	 except	that the body is executed only
	      while the	exit status of the first list is non-zero.

       while list do list done
	      A	while is a prechecked loop.  Its body is executed as often  as
	      the exit status of the first list	is zero.  The exit status of a
	      while statement is the last exit status of the list in the  body
	      of  the  loop;  if  the body is not executed, the	exit status is

       function	name { list }
	      Defines the function name.   See	Functions  below.   Note  that
	      redirections specified after a function definition are performed
	      whenever the function is executed, not when the function defini-
	      tion is executed.

       name () command
	      Mostly the same as function.  See	Functions below.

       time [ -p ] [ pipeline ]
	      The  time	 reserved  word	 is described in the Command Execution

       (( expression ))
	      The arithmetic expression	expression is evaluated; equivalent to
	      let  "expression".   See Arithmetic Expressions and the let com-
	      mand below.

       [[ expression ]]
	      Similar to the test and [	... ] commands (described later), with
	      the following exceptions:
		o    Field  splitting  and  file  name generation are not per-
		     formed on arguments.
		o    The -a (and) and -o (or) operators	are replaced  with  &&
		     and ||, respectively.
		o    Operators (e.g., -f, =, !,	etc.) must be unquoted.
		o    The  second  operand of !=	and = expressions are patterns
		     (e.g., the	comparison in
					[[ foobar = f*r	]]
		o    There are two additional binary operators:	< and >	 which
		     return  true  if their first string operand is less than,
		     or	greater	than, their  second  string  operand,  respec-
		o    The  single  argument  form  of  test, which tests	if the
		     argument has non-zero length, is  not  valid  -  explicit
		     operators must be always be used, e.g., instead of
					      [	str ]
					   [[ -n str ]]
		o    Parameter,	 command and arithmetic	substitutions are per-
		     formed as expressions are evaluated and  lazy  expression
		     evaluation	 is  used  for	the && and || operators.  This
		     means that	in the statement
				  [[ -r	foo && $(< foo)	= b*r ]]
		     the $(< foo) is evaluated if and only  if	the  file  foo
		     exists and	is readable.

       Quoting	is used	to prevent the shell from treating characters or words
       specially.  There are three methods of quoting:	First,	\  quotes  the
       following  character,  unless it	is at the end of a line, in which case
       both the	\ and the newline are stripped.	 Second, a  single  quote  (')
       quotes  everything  up  to the next single quote	(this may span lines).
       Third, a	double quote (") quotes	all characters,	except $, ` and	\,  up
       to  the	next unquoted double quote.  $ and ` inside double quotes have
       their usual meaning (i.e., parameter, command or	 arithmetic  substitu-
       tion)  except  no field splitting is carried out	on the results of dou-
       ble-quoted substitutions.  If a \ inside	a double-quoted	string is fol-
       lowed by	\, $, `	or ", it is replaced by	the second character; if it is
       followed	by a newline, both the \ and the newline are stripped;	other-
       wise, both the \	and the	character following are	unchanged.

       Note:  see  POSIX  Mode below for a special rule	regarding sequences of
       the form	"...`...\"...`..".

       There are two types of aliases:	normal	command	 aliases  and  tracked
       aliases.	  Command aliases are normally used as a short hand for	a long
       or often	used command.  The shell expands command aliases  (i.e.,  sub-
       stitutes	 the alias name	for its	value) when it reads the first word of
       a command.  An  expanded	 alias	is  re-processed  to  check  for  more
       aliases.	 If a command alias ends in a space or tab, the	following word
       is also checked for alias expansion.  The alias expansion process stops
       when  a word that is not	an alias is found, when	a quoted word is found
       or when an alias	word that is currently being expanded is found.

       The following command aliases are defined automatically by the shell:
	      autoload='typeset	-fu'
	      functions='typeset -f'
	      hash='alias -t'
	      history='fc -l'
	      integer='typeset -i'
	      login='exec login'
	      newgrp='exec newgrp'
	      nohup='nohup '
	      r='fc -e -'
	      stop='kill -STOP'
	      suspend='kill -STOP $$'
	      type='whence -v'

       Tracked aliases allow the shell to remember where it found a particular
       command.	  The  first  time  the	shell does a path search for a command
       that is marked as a tracked alias, it saves the full path of  the  com-
       mand.   The  next  time	the  command is	executed, the shell checks the
       saved path to see that it is still valid, and if	so,  avoids  repeating
       the path	search.	 Tracked aliases can be	listed and created using alias
       -t.  Note that changing the PATH	parameter clears the saved  paths  for
       all  tracked  aliases.	If  the	 trackall  option is set (i.e.,	set -o
       trackall	or set -h), the	shell tracks all commands.  This option	is set
       automatically for non-interactive shells.  For interactive shells, only
       the following commands are automatically	tracked: cat, cc,  chmod,  cp,
       date, ed, emacs,	grep, ls, mail,	make, mv, pr, rm, sed, sh, vi and who.

       The first step the shell	takes in executing a simple-command is to per-
       form  substitutions on the words	of the command.	 There are three kinds
       of substitution:	parameter, command and arithmetic.  Parameter  substi-
       tutions,	 which	are  described in detail in the	next section, take the
       form $name or ${...}; command substitutions take	the form $(command) or
       `command`;  and arithmetic substitutions	take the form $((expression)).

       If a substitution appears outside of double quotes, the results of  the
       substitution are	generally subject to word or field splitting according
       to the current value of the IFS parameter.  The IFS parameter specifies
       a  list	of characters which are	used to	break a	string up into several
       words; any characters from the set space, tab and newline  that	appear
       in  the IFS characters are called IFS white space.  Sequences of	one or
       more IFS	white space characters,	in combination with zero or  one  non-
       IFS white space characters delimit a field.  As a special case, leading
       and trailing IFS	white space is stripped	(i.e., no leading or  trailing
       empty  field is created by it); leading or trailing non-IFS white space
       does create an empty field.  Example: if	IFS is set to `<space>:',  the
       sequence	 of  characters	 `<space>A<space>:<space><space>B::D' contains
       four fields: `A', `B', `' and `D'.  Note	that if	the IFS	 parameter  is
       set to the null string, no field	splitting is done; if the parameter is
       unset, the default value	of space, tab and newline is used.

       The results of substitution are,	unless otherwise specified, also  sub-
       ject  to	brace expansion	and file name expansion	(see the relevant sec-
       tions below).

       A command substitution is replaced by the output	generated by the spec-
       ified  command,	which  is run in a subshell.  For $(command) substitu-
       tions, normal quoting rules are used when command is  parsed,  however,
       for the `command` form, a \ followed by any of $, ` or \	is stripped (a
       \ followed by any other character is unchanged).	 As a special case  in
       command	substitutions,	a command of the form <	file is	interpreted to
       mean substitute the contents of file ($(< foo) has the same  effect  as
       $(cat  foo),  but it is carried out more	efficiently because no process
       is started).
       NOTE: $(command)	expressions are	currently parsed by finding the	match-
       ing  parenthesis,  regardless of	quoting.  This will hopefully be fixed

       Arithmetic substitutions	are replaced by	the  value  of	the  specified
       expression.   For  example, the command echo $((2+3*4)) prints 14.  See
       Arithmetic Expressions for a description	of an expression.

       Parameters are shell variables; they can	be assigned values  and	 their
       values  can  be	accessed  using	a parameter substitution.  A parameter
       name is either one of the special single	punctuation or digit character
       parameters  described  below, or	a letter followed by zero or more let-
       ters or digits (`_' counts as a letter).	 The later form	can be treated
       as arrays by appending an array index of	the form: [expr] where expr is
       an arithmetic expression.  Array	indicies are currently limited to  the
       range 0 through 1023, inclusive.	 Parameter substitutions take the form
       $name, ${name} or ${name[expr]},	where name is a	 parameter  name.   If
       substitution  is	 performed  on a parameter (or an array	parameter ele-
       ment) that is not set, a	null string is substituted unless the  nounset
       option  (set  -o	 nounset  or  set  -u)	is set,	in which case an error

       Parameters can be assigned values in a  number  of  ways.   First,  the
       shell  implicitly  sets	some parameters	like #,	PWD, etc.; this	is the
       only way	the special single  character  parameters  are	set.   Second,
       parameters  are	imported  from	the  shell's  environment  at startup.
       Third, parameters can be	assigned values	on the command line, for exam-
       ple,  `FOO=bar'	sets  the  parameter  FOO  to  bar; multiple parameter
       assignments can be given	on a single command line and they can be  fol-
       lowed  by a simple-command, in which case the assignments are in	effect
       only for	the  duration  of  the	command	 (such	assignments  are  also
       exported,  see  below  for  implications	 of this).  Note that both the
       parameter name and the =	must be	unquoted for the shell to recognize  a
       parameter  assignment.	The  fourth way	of setting a parameter is with
       the export, readonly and	typeset	commands; see  their  descriptions  in
       the Command Execution section.  Fifth, for and select loops set parame-
       ters as well as the getopts, read and set -A commands.  Lastly, parame-
       ters  can  be  assigned values using assignment operators inside	arith-
       metic expressions (see  Arithmetic  Expressions	below)	or  using  the
       ${name=value} form of parameter substitution (see below).

       Parameters  with	 the export attribute (set using the export or typeset
       -x commands, or by parameter assignments	followed by  simple  commands)
       are  put	 in  the  environment  (see environ(5))	of commands run	by the
       shell as	name=value pairs.  The order in	which parameters appear	in the
       environment  of a command is unspecified.  When the shell starts	up, it
       extracts	parameters and their values from its environment and automati-
       cally sets the export attribute for those parameters.

       Modifiers can be	applied	to the ${name} form of parameter substitution:

	      if name is set and not null, it is substituted,  otherwise  word
	      is substituted.

	      if  name	is  set	 and  not null,	word is	substituted, otherwise
	      nothing is substituted.

	      if name is set and not null, it is substituted, otherwise	it  is
	      assigned word and	the resulting value of name is substituted.

	      if  name	is set and not null, it	is substituted,	otherwise word
	      is printed on standard error (preceded by	name:)	and  an	 error
	      occurs (normally causing termination of a	shell script, function
	      or .-script).  If	word is	omitted	the string `parameter null  or
	      not set' is used instead.

       In  the above modifiers,	the : can be omitted, in which case the	condi-
       tions only depend on name being set (as opposed to set and  not	null).
       If  word	 is needed, parameter, command,	arithmetic and tilde substitu-
       tion are	performed on it; if word is not	needed,	it is not evaluated.

       The following forms of parameter	substitution can also be used:

	      The number of positional parameters if name is *,	@  or  is  not
	      specified,  or the length	of the string value of parameter name.

       ${#name[*]}, ${#name[@]}
	      The number of elements in	the array name.

       ${name#pattern},	${name##pattern}
	      If pattern matches the beginning of the value of parameter name,
	      the  matched text	is deleted from	the result of substitution.  A
	      single # results in the shortest match, two #'s results  in  the
	      longest match.

       ${name%pattern},	${name%%pattern}
	      Like  ${..#..}  substitution, but	it deletes from	the end	of the

       The following special parameters	are implicitly set by  the  shell  and
       cannot be set directly using assignments:

       !      Process  id of the last background process started.  If no back-
	      ground processes have been started, the parameter	is not set.

       #      The number of positional parameters (i.e., $1, $2, etc.).

       $      The process ID of	the shell, or the PID of the original shell if
	      it is a subshell.

       -      The  concatenation of the	current	single letter options (see set
	      command below for	list of	options).

       ?      The exit status of the last non-asynchronous  command  executed.
	      If  the  last  command  was killed by a signal, $? is set	to 128
	      plus the signal number.

       0      The name the shell was invoked with (i.e., argv[0]), or the com-
	      mand-name	 if it was invoked with	the -c option and the command-
	      name was supplied, or the	file argument, if it was supplied.  If
	      the posix	option is not set, $0 is the name of the current func-
	      tion or script.

       1 ... 9
	      The first	nine positional	parameters that	were supplied  to  the
	      shell,  function or .-script.  Further positional	parameters may
	      be accessed using	${number}.

       *      All positional parameters	(except	 parameter  0),	 i.e.,	$1  $2
	      $3....   If  used	outside	of double quotes, parameters are sepa-
	      rate words (which	are subjected  to  word	 splitting);  if  used
	      within  double  quotes,  parameters  are	separated by the first
	      character	of the IFS parameter (or the empty string  if  IFS  is

       @      Same  as	$*,  unless  it	is used	inside double quotes, in which
	      case a separate word is generated	for each positional  parameter
	      -	 if  there  are	no positional parameters, no word is generated
	      ("$@" can	be used	to access arguments, verbatim, without loosing
	      null arguments or	splitting arguments with spaces).

       The following parameters	are set	and/or used by the shell:

       _ (underscore)
	      When  an external	command	is executed by the shell, this parame-
	      ter is set in the	environment of the new process to the path  of
	      the  executed  command.	In  interactive	use, this parameter is
	      also set in the parent shell to the last word  of	 the  previous
	      command.	 When  MAILPATH	messages are evaluated,	this parameter
	      contains the name	of the file that changed (see MAILPATH parame-
	      ter below).

       CDPATH Search  path for the cd built-in command.	 Works the same	way as
	      PATH for those directories not beginning with / in cd  commands.
	      Note  that  if CDPATH is set and does not	contain	. nor an empty
	      path, the	current	directory is not searched.

	      Set to the number	of columns on the terminal  or	window.	  Cur-
	      rently  set  to  the  cols  value	as reported by stty(1) if that
	      value is non-zero.  This parameter is used  by  the  interactive
	      line  editing  modes, and	by select, set -o and kill -l commands
	      to format	information in columns.

       EDITOR If the VISUAL parameter is not set, this parameter controls  the
	      command  line  editing  mode for interactive shells.  See	VISUAL
	      parameter	below for how this works.

       ENV    If this parameter	is found to be set after any profile files are
	      executed,	 the  expanded value is	used as	a shell	start-up file.
	      It typically contains function and alias definitions.

       ERRNO  Integer value of the shell's errno  variable  --	indicates  the
	      reason the last system call failed.

	      Not implemented yet.

	      If  set,	this parameter is assumed to contain the shell that is
	      to be used to execute commands that execve(2) fails  to  execute
	      and which	do not start with a `#!	shell' sequence.

       FCEDIT The editor used by the fc	command	(see below).

       FPATH  Like  PATH,  but	used when an undefined function	is executed to
	      locate the file defining the function.  It is also searched when
	      a	 command  can't	 be found using	PATH.  See Functions below for
	      more information.

	      The name of the file used	to store history.  When	 assigned  to,
	      history  is loaded from the specified file.  Also, several invo-
	      cations of the shell running on the same machine will share his-
	      tory if their HISTFILE parameters	all point at the same file.
	      NOTE:  if	 HISTFILE isn't	set, no	history	file is	used.  This is
	      different	  from	 the   original	  Korn	 shell,	  which	  uses
	      $HOME/.sh_history;  in future, pdksh may also use	a default his-
	      tory file.

	      The number of commands normally stored for history, default 128.

       HOME   The  default  directory for the cd command and the value substi-
	      tuted for	an unqualified ~ (see Tilde Expansion below).

       IFS    Internal field separator,	used during substitution  and  by  the
	      read  command, to	split values into distinct arguments; normally
	      set to space, tab	 and  newline.	 See  Substitution  above  for
	      Note:  this  parameter is	not imported from the environment when
	      the shell	is started.

	      The version of shell and the date	the version was	created	(read-
	      only).   See also	the version commands in	Emacs Editing Mode and
	      Vi Editing Mode sections,	below.

       LINENO The line number of the function or shell	script	that  is  cur-
	      rently being executed.

       LINES  Set to the number	of lines on the	terminal or window.

	      Not implemented yet.

       MAIL   If  set, the user	will be	informed of the	arrival	of mail	in the
	      named file.  This	parameter is ignored if	the MAILPATH parameter
	      is set.

	      How  often,  in  seconds,	 the  shell will check for mail	in the
	      file(s) specified	by MAIL	or MAILPATH.  If 0, the	 shell	checks
	      before each prompt.  The default is 600 (10 minutes).

	      A	list of	files to be checked for	mail.  The list	is colon sepa-
	      rated, and each file may be followed by a	? and a	message	to  be
	      printed  if new mail has arrived.	 Command, parameter and	arith-
	      metic substitution is performed on the message, and, during sub-
	      stitution,  the parameter	$_ contains the	name of	the file.  The
	      default message is you have mail in $_.

       OLDPWD The previous working directory.  Unset if	cd  has	 not  success-
	      fully  changed  directories  since  the shell started, or	if the
	      shell doesn't know where it is.

       OPTARG When using getopts,  it  contains	 the  argument	for  a	parsed
	      option, if it requires one.

       OPTIND The  index  of  the  last	argument processed when	using getopts.
	      Assigning	1 to this parameter causes getopts  to	process	 argu-
	      ments from the beginning the next	time it	is invoked.

       PATH   A	 colon	separated  list	 of directories	that are searched when
	      looking for commands and .'d files.  An empty  string  resulting
	      from  a  leading	or  trailing  colon, or	two adjacent colons is
	      treated as a `.',	the current directory.

	      If set, this parameter causes the	posix option  to  be  enabled.
	      See POSIX	Mode below.

       PPID   The process ID of	the shell's parent (readonly).

       PS1    PS1  is  the  primary prompt for interactive shells.  Parameter,
	      command and arithmetic substitutions are	performed,  and	 !  is
	      replaced with the	current	command	number (see fc command below).
	      A	literal	! can be put in	the prompt by placing !! in PS1.  Note
	      that  since  the command line editors try	to figure out how long
	      the prompt is (so	they know  how	far  it	 is  to	 edge  of  the
	      screen), escape codes in the prompt tend to mess things up.  You
	      can tell the shell not  to  count	 certain  sequences  (such  as
	      escape codes) by prefixing your prompt with a non-printing char-
	      acter (such as control-A)	followed by a carriage return and then
	      delimiting  the  escape  codes with this non-printing character.
	      If you don't have	any non-printing  characters,  you're  out  of
	      luck...  BTW, don't blame	me for this hack; it's in the original
	      ksh.  Default is `$ ' for	non-root users,	`# ' for root..

       PS2    Secondary	prompt string, by default `> ',	used when  more	 input
	      is needed	to complete a command.

       PS3    Prompt  used  by select statement	when reading a menu selection.
	      Default is `#? '.

       PS4    Used to prefix commands that are printed during execution	 trac-
	      ing  (see	 set -x	command	below).	 Parameter, command and	arith-
	      metic substitutions are performed	before it is printed.  Default
	      is `+ '.

       PWD    The  current  working  directory.	  Maybe	unset or null if shell
	      doesn't know where it is.

       RANDOM A	simple random number generator.	 Every time RANDOM  is	refer-
	      enced, it	is assigned the	next number in a random	number series.
	      The point	in the series can be set by assigning a	number to RAN-
	      DOM (see rand(3)).

       REPLY  Default  parameter  for  the read	command	if no names are	given.
	      Also used	in select loops	to store the value that	is  read  from
	      standard input.

	      The number of seconds since the shell started or,	if the parame-
	      ter has been assigned an integer value, the  number  of  seconds
	      since the	assignment plus	the value that was assigned.

       TMOUT  If  set to a positive integer in an interactive shell, it	speci-
	      fies the maximum number of seconds the shell will	wait for input
	      after  printing  the  primary  prompt  (PS1).   If  the  time is
	      exceeded,	the shell exits.

       TMPDIR The directory shell temporary files are  created	in.   If  this
	      parameter	is not set, or does not	contain	the absolute path of a
	      writable directory, temporary files are created in /tmp.

       VISUAL If set, this parameter controls the command  line	 editing  mode
	      for interactive shells.  If the last component of	the path spec-
	      ified in this parameter contains the string vi, emacs or	gmacs,
	      the  vi, emacs or	gmacs (Gosling emacs) editing mode is enabled,

   Tilde Expansion
       Tilde expansion,	which is done in parallel with parameter substitution,
       is done on words	starting with an unquoted ~.  The characters following
       the tilde, up to	the first /, if	any, are assumed to be a  login	 name.
       If the login name is empty, + or	-, the value of	the HOME, PWD, or OLD-
       PWD parameter is	substituted, respectively.   Otherwise,	 the  password
       file  is	 searched for the login	name, and the tilde expression is sub-
       stituted	with the user's	home directory.	 If  the  login	 name  is  not
       found  in the password file or if any quoting or	parameter substitution
       occurs in the login name, no substitution is performed.

       In parameter assignments	(those preceding  a  simple-command  or	 those
       occurring  in  the  arguments of	alias, export, readonly, and typeset),
       tilde expansion is done after any unquoted colon	(:), and  login	 names
       are also	delimited by colons.

       The  home  directory  of	previously expanded login names	are cached and
       re-used.	 The alias -d command may be used to list, change and  add  to
       this cache (e.g., `alias	-d fac=/usr/local/facilities; cd ~fac/bin').

   Brace Expansion (alternation)
       Brace expressions, which	take the form
       are  expanded to	N words, each of which is the concatenation of prefix,
       stri and	suffix (e.g., `a{c,b{X,Y},d}e'	expands	 to  four  word:  ace,
       abXe,  abYe,  and ade).	As noted in the	example, brace expressions can
       be nested and the resulting words are not  sorted.   Brace  expressions
       must contain an unquoted	comma (,) for expansion	to occur (i.e.,	{} and
       {foo} are not expanded).	 Brace expansion is carried out	after  parame-
       ter substitution	and before file	name generation.

   File	Name Patterns
       A  file	name  pattern is a word	containing one or more unquoted	? or *
       characters or [..] sequences.  Once brace expansion has been performed,
       the  shell replaces file	name patterns with the sorted names of all the
       files that match	the pattern (if	no  files  match,  the	word  is  left
       unchanged).  The	pattern	elements have the following meaning:

       ?      matches any single character.

       *      matches any sequence of characters.

       [..]   matches  any  of	the characters inside the brackets.  Ranges of
	      characters can be	specified by separating	two characters by a -,
	      e.g.,  [a0-9]  matches  the  letter a or any digit.  In order to
	      represent	itself,	a - must either	be quoted or the first or last
	      character	 in the	character list.	 Similarly, a ]	must be	quoted
	      or the first character in	the list if  it	 is  represent	itself
	      instead  of  the	end  of	the list.  Also, a !  appearing	at the
	      start of the list	has special meaning (see below), so to	repre-
	      sent itself it must be quoted or appear later in the list.

       [!..]  like [..], except	it matches any character not inside the	brack-

       *(pattern| ... |pattern)
	      matches any string of characters that matches zero or more occu-
	      rances   of   the	 specified  patterns.	Example:  the  pattern
	      *(foo|bar) matches the strings `',  `foo',  `bar',  `foobarfoo',

       +(pattern| ... |pattern)
	      matches  any string of characters	that matches one or more occu-
	      rances  of  the  specified  patterns.   Example:	 the   pattern
	      +(foo|bar)  matches the strings `foo', `bar', `foobarfoo', etc..

       ?(pattern| ... |pattern)
	      matches the empty	string or a string that	 matches  one  of  the
	      specified	  patterns.   Example:	the  pattern  ?(foo|bar)  only
	      matches the strings `', `foo' and	`bar'.

       @(pattern| ... |pattern)
	      matches a	string that matches one	 of  the  specified  patterns.
	      Example:	the  pattern @(foo|bar)	only matches the strings `foo'
	      and `bar'.

       !(pattern| ... |pattern)
	      matches any string that does not match one of the	specified pat-
	      terns.   Examples:  the  pattern	!(foo|bar) matches all strings
	      except `foo' and `bar'; the pattern !(*) matches no strings; the
	      pattern !(?)* matches all	strings	(think about it).

       Note that pdksh currently never matches . and .., but the original ksh,
       Bourne sh and bash do, so this may have to change (too bad).

       Note that none of the above pattern elements match either a period  (.)
       at the start of a file name or a	slash (/), even	if they	are explicitly
       used in a [..] sequence;	also, the names	. and ..  are  never  matched,
       even by the pattern .*.

       If  the	markdirs  option is set, any directories that result from file
       name generation are marked with a trailing /.

       The POSIX character classes (i.e., [:class-name:] inside	a [..] expres-
       sion) are not yet implemented.

   Input/Output	Redirection
       When  a	command	 is  executed, its standard input, standard output and
       standard	error (file descriptors	0, 1 and 2, respectively) are normally
       inherited  from	the  shell.   Three exceptions to this are commands in
       pipelines, for which standard input and/or standard  output  are	 those
       set  up by the pipeline,	asynchronous commands created when job control
       is disabled, for	which standard input  is  initially  set  to  be  from
       /dev/null,  and	commands  for  which any of the	following redirections
       have been specified:

       > file standard output is redirected to file.  If file does not	exist,
	      it  is  created;	if  it	does  exist, is	a regular file and the
	      noclobber	option is set, an error	occurs,	otherwise the file  is
	      truncated.   Note	 that  this  means the command cmd _ foo _ foo
	      will open	foo for	reading	and then truncate it when it opens  it
	      for writing, before cmd gets a chance to actually	read foo.

       >| file
	      same  as	>, except the file is truncated, even if the noclobber
	      option is	set.

       >> file
	      same as >, except	the file  an  existing	file  is  appended  to
	      instead  of being	truncated.  Also, the file is opened in	append
	      mode, so writes always go	to the end of the file (see  open(2)).

       < file standard	input  is  redirected  from  file, which is opened for

       <> file
	      same as <, except	the file is opened for reading and writing.

       << marker
	      after reading the	command	line containing	this kind of redirect-
	      ion  (called  a  here document), the shell copies	lines from the
	      command source into a  temporary	file  until  a	line  matching
	      marker is	read.  When the	command	is executed, standard input is
	      redirected from the  temporary  file.   If  marker  contains  no
	      quoted  characters,  the contents	of the temporary file are pro-
	      cessed as	if enclosed in double quotes each time the command  is
	      executed,	so parameter, command and arithmetic substitutions are
	      performed, along with backslash (\) escapes  for	$,  `,	\  and
	      \newline.	  If multiple here documents are used on the same com-
	      mand line, they are saved	in order.

       <<- marker
	      same as <<, except leading tabs are stripped from	lines  in  the
	      here document.

       <& fd  standard input is	duplicated from	file descriptor	fd.  fd	can be
	      a	single digit,  indicating  the	number	of  an	existing  file
	      descriptor, the letter p,	indicating the file descriptor associ-
	      ated with	the output of the current co-process, or the character
	      -, indicating standard input is to be closed.

       >& fd  same as <&, except the operation is done on standard output.

       In  any	of  the	 above redirections, the file descriptor that is redi-
       rected (i.e., standard input or	standard  output)  can	be  explicitly
       given  by  preceding  the  redirection with a single digit.  Parameter,
       command and arithmetic substitutions, tilde substitutions and  (if  the
       shell  is  interactive)	file  name generation are all performed	on the
       file, marker and	fd arguments of	redirections.  Note however, that  the
       results	of  any	file name generation are only used if a	single file is
       matched;	if multiple files match, the word  with	 the  unexpanded  file
       name  generation	 characters  is	used.  Note that in restricted shells,
       redirections which can create files cannot be used.

       For simple-commands, redirections may appear anywhere in	 the  command,
       for  compound-commands  (if  statements,	 etc.),	 any redirections must
       appear at the end.  Redirections	are processed after pipelines are cre-
       ated and	in the order they are given, so
	      cat /foo/bar 2>&1	> /dev/null | cat -n
       will print an error with	a line number prepended	to it.

   Arithmetic Expressions
       Integer arithmetic expressions can be used with the let command,	inside
       $((..)) expressions, inside array  references  (e.g.,  name[expr]),  as
       numeric	arguments  to the test command,	and as the value of an assign-
       ment to an integer parameter.

       Expression may contain alpha-numeric parameter identifiers, array  ref-
       erences,	and integer constants and may be combined with the following C
       operators (listed and grouped in	increasing order of precedence).

       Unary operators:
	      +	- ! ~ ++ --

       Binary operators:
	      =	*= /= %= += -= <<= >>= &= ^= |=
	      == !=
	      <	<= >= >
	      << >>
	      +	-
	      *	/ %

       Ternary operator:
	      ?: (precedence is	immediately higher than	assignment)

       Grouping	operators:
	      (	)

       Integer constants may be	specified with arbitrary bases using the nota-
       tion  base#number, where	base is	a decimal integer specifying the base,
       and number is a number in the specified base.

       The operators are evaluated as follows:

	      unary +
		     result is the argument (included for completeness).

	      unary -

	      !	     logical not; the result is	1 if argument is  zero,	 0  if

	      ~	     arithmetic	(bit-wise) not.

	      ++     increment;	 must be applied to a parameter	(not a literal
		     or	other expression) - the	parameter is incremented by 1.
		     When  used	as a prefix operator, the result is the	incre-
		     mented value of the parameter, when  used	as  a  postfix
		     operator, the result is the original value	of the parame-

	      ++     similar to	++, except the paramter	is decremented by 1.

	      ,	     separates two arithmetic expressions; the left hand  side
		     is	 evaluated first, then the right.  The result is value
		     of	the expression on the right hand side.

	      =	     assignment; variable on the left is set to	the  value  on
		     the right.

	      *= /= %= += -= <<= >>= &=	^= |=
		     assignment	 operators;  _var_ _op_= _expr_	is the same as
		     _var_ = _var_ _op_	( _expr_ ).

	      ||     logical or; the result is 1 if either  argument  is  non-
		     zero,  0 if not.  The right argument is evaluated only if
		     the left argument is zero.

	      &&     logical and; the result is	1 if both arguments  are  non-
		     zero,  0 if not.  The right argument is evaluated only if
		     the left argument is non-zero.

	      |	     arithmetic	(bit-wise) or.

	      ^	     arithmetic	(bit-wise) exclusive-or.

	      &	     arithmetic	(bit-wise) and.

	      ==     equal; the	result is 1 if both arguments are equal, 0  if

	      !=     not equal;	the result is 0	if both	arguments are equal, 1
		     if	not.

	      <	     less than;	the result is 1	if the left argument  is  less
		     than the right, 0 if not.

	      <= >= >
		     less  than	or equal, greater than or equal, greater than.
		     See <.

	      << >>  shift left	(right); the result is the left	argument  with
		     its  bits shifted left (right) by the amount given	in the
		     right argument.

	      +	- * /
		     addition, subtraction, multiplication, and	division.

	      %	     remainder;	the result is the remainder of the division of
		     the  left	argument by the	right.	The sign of the	result
		     is	unspecified if either argument is negative.

	      _arg1_ ? _arg2_ :	_arg3_
		     if	_arg1_ is non-zero, the	result	is  _arg2_,  otherwise

       A  co-process,  which is	a pipeline created with	the |& operator, is an
       asynchronous process that the shell can both write to (using print  -p)
       and  read from (using read -p).	The input and output of	the co-process
       can also	be manipulated using >&p and <&p  redirections,	 respectively.
       Once  a co-process has been started, another can't be started until the
       co-process exits, or until the co-process  input	 has  been  redirected
       using  an exec n>&p redirection.	 If a co-process's input is redirected
       in this way, the	next co-process	to be started will  share  the	output
       with  the first co-process, unless the output of	the initial co-process
       has been	redirected using an exec n<&p redirection.

       Some notes concerning co-processes:
	 o    the only way to close the	co-process input  (so  the  co-process
	      reads  an	 end-of-file)  is  to redirect the input to a numbered
	      file descriptor and then close that file descriptor (e.g.,  exec
	      3>&p;exec	3>&-).
	 o    in  order	 for  co-processes to share a common output, the shell
	      must keep	the write portion of the output	pipe open.  This means
	      that  end	 of  file  will	not be detected	until all co-processes
	      sharing the co-process output have exited	(when they  all	 exit,
	      the  shell closes	its copy of the	pipe).	This can be avoided by
	      redirecting the output to	a numbered file	 descriptor  (as  this
	      also causes the shell to close its copy).	 Note that this	behav-
	      iour is slightly different from the original  Korn  shell	 which
	      closes  its  copy	of the write portion of	the co-processs	output
	      when the most recently started co-process	(instead of  when  all
	      sharing co-processes) exits.
	 o    print -p will ignore SIGPIPE signals during writes if the	signal
	      is not being trapped or ignored; the same	is not true if the co-
	      process input has	been duplicated	to another file	descriptor and
	      print -un	is used.

       Functions are defined using either Korn shell function name  syntax  or
       the  Bourne/POSIX  shell	 name()	 syntax	 (see below for	the difference
       between the two forms).	Functions are like .-scripts in	that they  are
       executed	 in  the current environment, however, unlike .-scripts, shell
       arguments (i.e.,	positional parameters, $1,  etc.)  are	never  visible
       inside  them.  When the shell is	determining the	location of a command,
       functions are searched after special built-in commands, and before reg-
       ular and	non-regular built-ins, and before the PATH is searched.

       An  existing  function  may be deleted using unset -f function-name.  A
       list of functions can be	obtained using typeset	+f  and	 the  function
       definitions  can	 be  listed  using  typeset -f.	 autoload (which is an
       alias for typeset -fu) may be used to create undefined functions;  when
       an  undefined  function is executed, the	shell searches the path	speci-
       fied in the FPATH parameter for a file with the same name as the	 func-
       tion,  which,  if  found	 is read and executed.	If after executing the
       file, the named function	is found to be defined,	the function  is  exe-
       cuted,  otherwise,  the	normal	command	search is continued (i.e., the
       shell searches the regular built-in command table and PATH).  Note that
       if  a command is	not found using	PATH, an attempt is made to autoload a
       function	using FPATH (this is an	undocumented feature of	 the  original
       Korn shell).

       Functions  can  have two	attributes, trace and export, which can	be set
       with typeset -ft	and typeset -fx, respectively.	When a traced function
       is  executed,  the shell's xtrace option	is turned on for the functions
       duration, otherwise the	xtrace	option	is  turned  off.   The	export
       attribute  of  functions	 is  currently not used.  In the original Korn
       shell, exported functions are visible to	shell scripts  that  are  exe-

       Since  functions	are executed in	the current shell environment, parame-
       ter assignments made inside functions are visible  after	 the  function
       completes.   If this is not the desired effect, the typeset command can
       be used inside a	function to create a local parameter.  Note that  spe-
       cial parameters (e.g., $$, $!) can't be scoped in this way.

       The  exit  status of a function is that of the last command executed in
       the function.  A	function can be	made to	finish immediately  using  the
       return  command;	 this  may also	be used	to explicitly specify the exit

       Functions defined with the function reserved word are  treated  differ-
       ently  in  the  following ways from functions defined with the () nota-
	 o    the $0 parameter is set to the name  of  the  function  (Bourne-
	      style functions leave $0 untouched).
	 o    parameter	 assignments preceeding	function calls are not kept in
	      the shell	environment  (executing	 Bourne-style  functions  will
	      keep assignments).
	 o    OPTIND  is  saved/reset  and restored on entry and exit from the
	      function so getopts can be used properly both inside and outside
	      the  function (Bourne-style functions leave OPTIND untouched, so
	      using getopts inside a function interferes  with	using  getopts
	      outside the function).  In the future, the following differences
	      will also	be added:
	 o    A	separate trap/signal environment will be used during the  exe-
	      cution  of  functions.   This  will mean that traps set inside a
	      function will not	affect the shell's traps and signals that  are
	      not  ignored  in	the shell (but may be trapped) will have their
	      default effect in	a function.
	 o    The EXIT trap, if	set in a function, will	be executed after  the
	      function returns.

   POSIX Mode
       The  shell  is  intended	to be POSIX compliant, however,	in some	cases,
       POSIX behaviour is contrary either to the original Korn shell behaviour
       or to user convenience.	How the	shell behaves in these cases is	deter-
       mined by	the state of the posix option (set -o posix) --	if it  is  on,
       the POSIX behaviour is followed,	otherwise it is	not.  The posix	option
       is set automatically when the shell starts up if	the  environment  con-
       tains  the  POSIXLY_CORRECT parameter.  (The shell can also be compiled
       so that it is in	POSIX mode by default, however	this  is  usually  not

       The following is	a list of things that are affected by the state	of the
       posix option:
	 o    \" inside	double quoted `..`  command  substitutions:  in	 posix
	      mode,  the \" is interpreted when	the command is interpreted; in
	      non-posix	mode, the backslash is	stripped  before  the  command
	      substitution  is interpreted.  For example, echo "`echo \"hi\"`"
	      produces `"hi"' in posix mode, `hi' in non-posix mode.  To avoid
	      problems,	use the	$(...)	form of	command	substitution.
	 o    kill  -l	output:	 in  posix mode, signal	names are listed one a
	      single line;  in	non-posix  mode,  signal  numbers,  names  and
	      descriptions  are	 printed  in columns.  In future, a new	option
	      (-v perhaps) will	be added to distinguish	the two	behaviours.
	 o    fg exit status: in posix mode, the exit status is	0 if no	errors
	      occur;  in  non-posix  mode, the exit status is that of the last
	      foregrounded job.
	 o    eval exit	status:	if eval	gets to	see an	empty  command	(e.g.,
	      eval  "`false`"),	 its  exit status in posix mode	will be	0.  In
	      non-posix	mode, it will be the exit status of the	 last  command
	      substitution that	was done in the	processing of the arguments to
	      eval (or 0 if there were no command substitutions).
	 o    getopts: in posix	mode, options must start with  a  -;  in  non-
	      posix mode, options can start with either	- or +.
	 o    brace  expansion	(also  known  as  alternation):	in posix mode,
	      brace expansion is disabled; in non-posix	mode, brace  expansion
	      enabled.	Note that set -o posix (or setting the POSIXLY_CORRECT
	      parameter) automatically turns the braceexpand option off,  how-
	      ever it can be explicitly	turned on later.
	 o    set  -: in posix mode, this does not clear the verbose or	xtrace
	      options; in non-posix mode, it does.
	 o    set exit status: in posix	mode, the exit status of set is	 0  if
	      there  are no errors; in non-posix mode, the exit	status is that
	      of any command substitutions performed  in  generating  the  set
	      command.	 For  example,	`set  -- `false`; echo $?' prints 0 in
	      posix mode, 1 in non-posix mode.	This construct is used in most
	      shell scripts that use the old getopt(1) command.
	 o    argument	expansion of alias, export, readonly, and typeset com-
	      mands: in	posix mode, normal argument expansion  done;  in  non-
	      posix  mode,  field splitting, file globing, brace expansion and
	      (normal) tilde expansion are turned off,	and  assignment	 tilde
	      expansion	is turned on.
	 o    signal specification: in posix mode, signals can be specified as
	      digits only if signal numbers match POSIX	values	(i.e.,	HUP=1,
	      INT=2,  QUIT=3,  ABRT=6,	KILL=9,	ALRM=14, and TERM=15); in non-
	      posix mode, signals can be always	digits.
	 o    alias expansion: in posix	mode, alias expansion is only  carried
	      out  when	reading	command	words; in non-posix mode, alias	expan-
	      sion is carried out on any word following	an alias that ended in
	      a	space.	For example, the following for loop
	      alias a='for ' i='j'
	      a	i in 1 2; do echo i=$i j=$j; done
       uses parameter i	in posix mode, j in non-posix mode.
	 o    test:  in	posix mode, the	expression "-t"	(preceded by some num-
	      ber of "!" arguments) is always true as it is a non-zero	length
	      string;  in  non-posix  mode, it tests if	file descriptor	1 is a
	      tty (i.e., the fd	argument to the	-t test	may be	left  out  and
	      defaults to 1).

   Command Execution
       After  evaluation of command line arguments, redirections and parameter
       assignments, the	type of	command	is determined: a special  built-in,  a
       function,  a  regular  built-in	or the name of a file to execute found
       using the PATH parameter.  The checks are  made	in  the	 above	order.
       Special	built-in  commands differ from other commands in that the PATH
       parameter is not	used to	find them, an error during their execution can
       cause  a	 non-interactive  shell	to exit	and parameter assignments that
       are specified before the	command	are kept after the command  completes.
       Just to confuse things, if the posix option is turned off (see set com-
       mand below) some	special	commands are very special  in  that  no	 field
       splitting,  file	 globing,  brace expansion nor tilde expansion is pre-
       formed on arguments that	look like assignments.	Regular	built-in  com-
       mands are different only	in that	the PATH parameter is not used to find

       The original ksh	and POSIX differ somewhat in which commands  are  con-
       sidered special or regular:

       POSIX special commands

	      .		 continue   exit       return	  trap
	      :		 eval	    export     set	  unset
	      break	 exec	    readonly   shift

       Additional ksh special commands

	      builtin	 times	    typeset

       Very special commands (non-posix	mode)

	      alias	 readonly   set	       typeset

       POSIX regular commands

	      alias	 command    fg	       kill	  umask
	      bg	 false	    getopts    read	  unalias
	      cd	 fc	    jobs       true	  wait

       Additional ksh regular commands

	      [		 let	    pwd	       ulimit
	      echo	 print	    test       whence

       In  the	future,	the additional ksh special and regular commands	may be
       treated differently from	the POSIX special and regular commands.

       Once the	type of	the command has	 been  determined,  any	 command  line
       parameter  assignments  are  performed and exported for the duration of
       the command.

       The following describes the special and regular built-in	commands:

       . file [arg1 ...]
	      Execute the commands in file in the  current  environment.   The
	      file  is	searched for in	the directories	of PATH.  If arguments
	      are given, the positional	parameters may be used to access  them
	      while  file  is  being executed.	If no arguments	are given, the
	      positional parameters are	those of the environment  the  command
	      is used in.

       : [ ... ]
	      The null command.	 Exit status is	set to zero.

       alias [ -d | +-t	[-r] ] [+-px] [+-] [name1[=value1] ...]
	      Without  arguments, alias	lists all aliases.  For	any name with-
	      out a value, the existing	alias is  listed.   Any	 name  with  a
	      value defines an alias (see Aliases above).

	      When  listing  aliases,  one  of	two formats is used: normally,
	      aliases are listed as name=value,	 where	value  is  quoted;  if
	      options were preceded with + or a	lone + is given	on the command
	      line, only name is printed.  In addition,	if the	-p  option  is
	      used, each alias is prefixed with	the string "alias ".

	      The -x option sets (+x clears) the export	attribute of an	alias,
	      or, if no	names are given, lists the  aliases  with  the	export
	      attribute	(exporting an alias has	no affect).

	      The   -t	option	indicates  that	 tracked  aliases  are	to  be
	      listed/set (values specified on the command line are ignored for
	      tracked  aliases).   The	-r  option  indicates that all tracked
	      aliases are to be	reset.

	      The -d causes directory aliases, which are used in tilde	expan-
	      sion, to be listed or set	(see Tilde Expansion above).

       bg [job ...]
	      Resume  the  specified  stopped job(s) in	the background.	 If no
	      jobs are specified, %+ is	assumed.  This command is only	avail-
	      able  on	systems	 which	support	 job control.  See Job Control
	      below for	more information.

       bind [-m] [key[=editing-command]	...]
	      Set  or  view  the  current  emacs  command  editing  key	 bind-
	      ings/macros.   See  Emacs	 Editing  Mode	below  for  a complete

       break [level]
	      break exits the levelth inner most for, select, until, or	 while
	      loop.  level defaults to 1.

       builtin command [arg1 ...]
	      Execute the built-in command command.

       cd [-LP]	[dir]
	      Set  the	working	 directory to dir.  If the parameter CDPATH is
	      set, it lists directories	to search in for dir.  dir.  An	 empty
	      entry  in	 the  CDPATH  entry means the current directory.  If a
	      non-empty	directory from CDPATH is used, the resulting full path
	      is  printed  to  standard	 output.   If dir is missing, the home
	      directory	$HOME is used.	If dir	is  -,	the  previous  working
	      directory	is used	(see OLDPWD parameter).	 If -L option (logical
	      path) is used or if the physical option (see set command	below)
	      isn't set, references to .. in dir are relative to the path used
	      get to the directory.  If	-P option (physical path) is  used  or
	      if  the physical option is set, .. is relative to	the filesystem
	      directory	tree.  The PWD and OLDPWD parameters  are  updated  to
	      reflect the current and old wording directory, respectively.

       cd [-LP]	old new
	      The  string new is substituted for old in	the current directory,
	      and the shell attempts to	change to the new directory.

       command [-pvV] cmd [arg1	...]
	      If neither the -v	nor -V options	are  given,  cmd  is  executed
	      exactly  as  if  the  command  had  not been specified, with two
	      exceptions: first, cmd cannot be a shell function,  and  second,
	      special  built-in	 commands  lose	their specialness (i.e., redi-
	      rection and utility errors do not	cause the shell	to  exit,  and
	      command  assignments  are	 not  permanent).  If the -p option is
	      given, a default search path is  used  instead  of  the  current
	      value  of	 PATH  (the actual value of the	default	path is	system
	      dependent: on POSIXish systems, it is the	value returned by
				      getconf CS_PATH

	      If the -v	option is given, instead of executing cmd, information
	      about  what would	be executed is given (and the same is done for
	      arg1 ...): for special and regular built-in commands  and	 func-
	      tions,  their  names  are	simply printed,	for aliases, a command
	      that defines them	is printed, and	for commands found by  search-
	      ing the PATH parameter, the full path of the command is printed.
	      If no command is be found, (i.e.,	the path search	fails),	 noth-
	      ing is printed and command exits with a non-zero status.	The -V
	      option is	like the -v option, except it is more verbose.

       continue	[levels]
	      continue jumps to	the beginning of the levelth inner  most  for,
	      select, until, or	while loop.  level defaults to 1.

       echo [-neE] [arg	...]
	      Prints  its  arguments  (separated by spaces) followed by	a new-
	      line, to standard	out.  The newline is suppressed	if any of  the
	      arguments	 contain the backslash sequence	\c.  See print command
	      below for	a list of other	backslash sequences  that  are	recog-

	      The  options  are	 provided  for	compatibility  with  BSD shell
	      scripts: -n suppresses the trailing newline,  -e	enables	 back-
	      slash interpretation (a no-op, since this	is normally done), and
	      -E which suppresses backslash interpretation.

       eval command ...
	      The arguments are	concatenated (with  spaces  between  them)  to
	      form a single string which the shell then	parses and executes in
	      the current environment.

       exec [command [arg ...]]
	      The command is executed without  forking,	 replacing  the	 shell

	      If  no  arguments	are given, any IO redirection is permanent and
	      the shell	is not replaced.  Any file descriptors greater than  2
	      which are	opened or dup(2)-ed in this way	are not	made available
	      to other executed	commands (i.e.,	commands that are not built-in
	      to the shell).  Note that	the Bourne shell differs here: it does
	      pass these file descriptors on.

       exit [status]
	      The shell	exits with the specified exit status.	If  status  is
	      not  specified,  the  exit  status is the	current	value of the ?

       export [-p] [parameter[=value]] ...
	      Sets the export attribute	of  the	 named	parameters.   Exported
	      parameters  are  passed in the environment to executed commands.
	      If values	are specified, the named parameters also assigned.

	      If no parameters are specified, the names	of all parameters with
	      the  export  attribute  are  printed one per line, unless	the -p
	      option is	used, in  which	 case  export  commands	 defining  all
	      exported parameters, including their values, are printed.

       false  A	command	that exits with	a non-zero status.

       fc [-e editor | -l [-n]]	[-r] [first [last]]
	      first  and  last select commands from the	history.  Commands can
	      be selected by history number, or	a string specifying  the  most
	      recent  command  starting	with that string.  The -l option lists
	      the command on stdout, and -n inhibits the default command  num-
	      bers.   The  -r  option reverses the order of the	list.  Without
	      -l, the selected commands	are edited  by	the  editor  specified
	      with  the	-e option, or if no -e is specified, the editor	speci-
	      fied by the FCEDIT parameter (if	this  parameter	 is  not  set,
	      /bin/ed is used),	and then executed by the shell.

       fc [-e -	| -s] [-g] [old=new] [prefix]
	      Re-execute   the	selected  command  (the	 previous  command  by
	      default) after performing	the optional substitution of old  with
	      new.   If	 -g  is	specified, all occurrences of old are replaced
	      with new.	 This command is usually accessed with the  predefined
	      alias r='fc -e -'.

       fg [job ...]
	      Resume  the  specified job(s) in the foreground.	If no jobs are
	      specified, %+ is assumed.	 This command  is  only	 available  on
	      systems  which  support  job control.  See Job Control below for
	      more information.

       getopts optstring name [arg ...]
	      getopts is used by shell procedures to parse the specified argu-
	      ments  (or positional parameters,	if no arguments	are given) and
	      to check for legal options.  optstring contains the option  let-
	      ters that	getopts	is to recognize.  If a letter is followed by a
	      colon, the option	is expected to have an argument.  Options that
	      do  not  take arguments may be grouped in	a single argument.  If
	      an option	takes an argument and the option character is not  the
	      last  character of the argument it is found in, the remainder of
	      the argument is taken to be the  option's	 argument,  otherwise,
	      the next argument	is the option's	argument.

	      Each  time  getopts is invoked, it places	the next option	in the
	      shell parameter name and the index of the	next  argument	to  be
	      processed	 in  the  shell	 parameter  OPTIND.  If	the option was
	      introduced with a	+, the option placed in	name is	prefixed  with
	      a	 +.  When an option requires an	argument, getopts places it in
	      the shell	parameter OPTARG.  When	an illegal option or a missing
	      option  argument	is  encountered	 a question mark or a colon is
	      placed in	name (indicating an illegal option  or	missing	 argu-
	      ment,  respectively)  and	 OPTARG	is set to the option character
	      that caused the problem.	An error message is  also  printed  to
	      standard error if	optstring does not begin with a	colon.

	      When the end of the options is encountered, getopts exits	with a
	      non-zero exit status.  Options  end  at  the  first  (non-option
	      argument)	 argument  that	 does not start	with a -, or when a --
	      argument is encountered.

	      Option parsing can be reset by setting OPTIND to 1 (this is done
	      automatically  whenever  the  shell  or  a  shell	 procedure  is

	      Warning: Changing	the value of the shell parameter OPTIND	 to  a
	      value other than 1, or parsing different sets of arguments with-
	      out resetting OPTIND may lead to unexpected results.

       hash [-r] [name ...]
	      Without arguments, any hashed executable command	pathnames  are
	      listed.	The -r option causes all hashed	commands to be removed
	      from the hash table.  Each name is searched as  if  it  where  a
	      command  name and	added to the hash table	if it is an executable

       jobs [-lpn] [job	...]
	      Display information about	the specified jobs;  if	 no  jobs  are
	      specified,  all jobs are displayed.  The -n option causes	infor-
	      mation to	be displayed only for jobs  that  have	changed	 state
	      since  the  last	notification.	If  the	-l option is used, the
	      process-id of each process in a job  is  also  listed.   The  -p
	      option  causes only the process group of each job	to be printed.
	      See Job Control below for	the format of job  and	the  displayed

       kill [-s	signame	| -signum | -signame ] { job | pid | -pgrp } ...
	      Send the specified signal	to the specified jobs, process ids, or
	      process groups.  If no signal is specified, the signal  TERM  is
	      sent.   If  a  job is specified, the signal is sent to the job's
	      process group.  See Job Control below for	the format of job.

       kill -l [exit-status ...]
	      Print the	name of	the signal that	killed a process which	exited
	      with  the	 specified  exit-statuses.  If no arguments are	speci-
	      fied, a list of all the  signals,	 their	numbers	 and  a	 short
	      description of them are printed.

       let [expression ...]
	      Each  expression is evaluated, see Arithmetic Expressions	above.
	      If all expressions are successfully evaluated, the  exit	status
	      is  0  (1)  if the last expression evaluated to non-zero (zero).
	      If an error occurs  during  the  parsing	or  evaluation	of  an
	      expression,  the	exit  status is	greater	than 1.	 Since expres-
	      sions may	need to	be quoted, (( expr )) is syntactic  sugar  for
	      let "expr".

       print [-nprsun |	-R [-en]] [argument ...]
	      Print  prints its	arguments on the standard output, separated by
	      spaces, and terminated with a newline.  The -n option suppresses
	      the  newline.   By  default,  certain  C escapes are translated.
	      These include \b,	\f, \n,	\r, \t,	\v, and	\0### (# is  an	 octal
	      digit, of	which there may	be 0 to	3).  \c	is equivalent to using
	      the -n option.  \	expansion may be inhibited with	the -r option.
	      The  -s  option  prints  to the history file instead of standard
	      output, the -u option prints to file descriptor n	(n defaults to
	      1	 if  omitted), and the -p option prints	to the co-process (see
	      Co-Processes above).

	      The -R option is used to emulate,	to some	degree,	the  BSD  echo
	      command, which does not process \	sequences unless the -e	option
	      is given.	 As above, the -n option suppresses the	trailing  new-

       pwd [-LP]
	      Print the	present	working	directory.  If -L option is used or if
	      the physical option (see set command below) isn't	set, the logi-
	      cal  path	 is  printed (i.e., the	path used to cd	to the current
	      directory).  If -P option	(physical path)	 is  used  or  if  the
	      physical	option is set, the path	determined from	the filesystem
	      (by following ..	directories to the root	directory) is printed.

       read [-prsun] [parameter	...]
	      Reads  a	line  of  input	from standard input, separate the line
	      into fields using	the IFS	parameter  (see	 Substitution  above),
	      and assign each field to the specified parameters.  If there are
	      more parameters than fields, the extra  parameters  are  set  to
	      null,  or	 alternatively,	 if there are more fields than parame-
	      ters, the	 last  parameter  is  assigned	the  remaining	fields
	      (inclusive  of  any  separating  spaces).	  If no	parameters are
	      specified, the REPLY parameter is	used.  If the input line  ends
	      in a backslash and the -r	option was not used, the backslash and
	      newline are stripped and more input is read.   If	 no  input  is
	      read, read exits with a non-zero status.

	      The  first  parameter  may  have	a  question  mark and a	string
	      appended to it, in which case the	string is  used	 as  a	prompt
	      (printed	to  standard  error  before  any input is read)	if the
	      input is a tty (e.g., read nfoo?'number of foos: ').

	      The -un and -p options cause input to be read from file descrip-
	      tor n or the current co-process (see Co-Processes	above for com-
	      ments on this), respectively.  If	the -s option is  used,	 input
	      is saved to the history file.

       readonly	[-p] [parameter[=value]] ...
	      Sets  the	readonly attribute of the named	parameters.  If	values
	      are given,  parameters  are  set	to  them  before  setting  the
	      attribute.   Once	 a  parameter  is  made	readonly, it cannot be
	      unset and	its value cannot be changed.

	      If no parameters are specified, the names	of all parameters with
	      the  readonly  attribute are printed one per line, unless	the -p
	      option is	used, in which case  readonly  commands	 defining  all
	      readonly parameters, including their values, are printed.

       return [status]
	      Returns  from  a	function or . script, with exit	status status.
	      If no status is given, the exit status of	the last executed com-
	      mand is used.  If	used outside of	a function or .	script,	it has
	      the same effect as exit.	Note that pdksh	 treats	 both  profile
	      and  $ENV	files as . scripts, while the original Korn shell only
	      treats profiles as . scripts.

       set [+-abCefhkmnpsuvxX] [+-o [option]] [+-A name] [--] [arg ...]
	      The set command can be used  to  set  (-)	 or  clear  (+)	 shell
	      options,	set the	positional parameters, or set an array parame-
	      ter.  Options can	be changed using the +-o option	syntax,	 where
	      option is	the long name of an option, or using the +-letter syn-
	      tax, where letter	is the option's	single letter  name  (not  all
	      options  have  a single letter name).  The following table lists
	      both option letters (if they exist) and long names along with  a
	      description of what the option does.

	       -A				Sets the elements of the array
						parameter name to arg ...;  If
						-A is used, the	array is reset
						(i.e., emptied)	first;	if  +A
						is  used, the first N elements
						are set	(where N is the	number
						of  args),  the	 rest are left
	       -a	  allexport		all new	parameters are created
						with the export	attribute
	       -b	  notify		Print  job  notification  mes-
						sages asynchronously,  instead
						of  just  before  the  prompt.
						Only used if  job  control  is
						enabled	(-m).
	       -C	  noclobber		Prevent	  >  redirection  from
						overwriting existing files (>|
						must be	used to	force an over-
	       -e	  errexit		Exit (after executing the  ERR
						trap)  as  soon	 as  an	 error
						occurs	or  a  command	 fails
						(i.e.,	exits  with a non-zero
						status).  This does not	 apply
						to  commands whose exit	status
						is  explicitly	tested	by   a
						shell  construct  such	as if,
						until, while, && or ||	state-
	       -f	  noglob		Do  not	 expand	file name pat-
	       -h	  trackall		Create tracked aliases for all
						executed commands (see Aliases
						above).	  On  by  default  for
						non-interactive	shells.
	       -i	  interactive		Enable interactive mode	- this
						can only be set/unset when the
						shell is invoked.
	       -k	  keyword		Parameter assignments are rec-
						ognized	anywhere in a command.
	       -l	  login			The  shell  is a login shell -
						this  can  only	 be  set/unset
						when the shell is invoked (see
						Shell Startup above).
	       -m	  monitor		Enable	job  control  (default
						for interactive	shells).
	       -n	  noexec		Do  not	execute	any commands -
						useful for checking the	syntax
						of  scripts (ignored if	inter-

	       -p	  privileged		Set automatically if, when the
						shell  starts, the read	uid or
						gid does not match the	effec-
						tive uid or gid, respectively.
						See Shell Startup above	for  a
						description   of   what	  this
	       -r	  restricted		Enable restricted mode -- this
						option	can  only be used when
						the  shell  is	invoked.   See
						Shell	Startup	 above	for  a
						description   of   what	  this
	       -s	  stdin			If  used  when	the  shell  is
						invoked,  commands  are	  read
						from   standard	  input.   Set
						automatically if the shell  is
						invoked	with no	arguments.

						When  -s  is  used  in the set
						command, it causes the	speci-
						fied  arguments	 to  be	sorted
						before assigning them  to  the
						positional  parameters	(or to
						array name, if -A is used).
	       -u	  nounset		Referencing of an unset	param-
						eter  is  treated as an	error,
						unless one of the -,  +	 or  =
						modifiers is used.
	       -v	  verbose		Write  shell input to standard
						error as it is read.
	       -x	  xtrace		Print commands	and  parameter
						assignments when they are exe-
						cuted, preceded	by  the	 value
						of PS4.
	       -X	  markdirs		Mark directories with a	trail-
						ing / during file name genera-
			  bgnice		Background  jobs  are run with
						lower priority.
			  braceexpand		Enable brace  expansion	 (aka,
			  emacs			Enable	BRL emacs-like command
						line   editing	  (interactive
						shells	only); see Emacs Edit-
						ing Mode.
			  gmacs			Enable	 gmacs-like   (Gosling
						emacs)	command	 line  editing
						(interactive   shells	only);
						currently  identical  to emacs
						editing	except that  transpose
						(^T)   acts  slightly  differ-
			  ignoreeof		The shell  will	 not  (easily)
						exit  on  when	end-of-file is
						read, exit must	be  used.   To
						avoid	infinite   loops,  the
						shell will exit	if eof is read
						13 times in a row.
			  nohup			Do  not	kill running jobs with
						a  HUP	signal	when  a	 login
						shell  exists.	 Currently set
						by  default,  but  this	  will
						change	in  the	 future	 to be
						compatible with	 the  original
						Korn shell (which doesn't have
						this option, but does send the
						HUP signal).
			  nolog			No  effect  -  in the original
						Korn  shell,   this   prevents
						function    definitions	  from
						being stored  in  the  history

			  physical		Causes the cd and pwd commands
						to use `physical'  (i.e.,  the
						filesystem's)  ..  directories
						instead	of `logical'  directo-
						ries (i.e.,  the shell handles
						.., which allows the  user  to
						be  obliveous of symlink links
						to  directories).   Clear   by
						default.   Note	 that  setting
						this option  does  not	effect
						the  current  value of the PWD
						parameter; only	the cd command
						changes	 PWD.	See the	cd and
						pwd commands  above  for  more
			  posix			Enable	posix mode.  See POSIX
						Mode above.
			  vi			Enable	vi-like	 command  line
						editing	  (interactive	shells
			  viraw			No effect -  in	 the  original
						Korn  shell,  unless viraw was
						set, the vi command line  mode
						would  let  the	 tty driver do
						the work until	ESC  (^[)  was
						entered.   pdksh  is always in
						viraw mode.
			  vi-esccomplete	In vi command line editing, do
						command	/ file name completion
						when escape (^[) is entered in
						command	mode.
			  vi-show8		Prefix	 characters  with  the
						eighth bit set with `M-'.   If
						this  option is	not set, char-
						acters in  the	range  128-160
						are  printed  as is, which may
						cause problems.
			  vi-tabcomplete	In vi command line editing, do
						command	/ file name completion
						when tab (^I)  is  entered  in
						insert mode.

	      These  options  can  also	 be used upon invocation of the	shell.
	      The current set of options (with single  letter  names)  can  be
	      found  in	the parameter -.  set -o with no option	name will list
	      all the options and whether each is on or	off; set +o will print
	      the long names of	all options that are currently on.

	      Remaining	 arguments,  if	any, are positional parameters and are
	      assigned,	in order, to the positional parameters	(i.e.,	1,  2,
	      etc.).   If options are ended with -- and	there are no remaining
	      arguments, all positional	parameters are cleared.	 If no options
	      or  arguments  are  given,  then	the  values  of	 all names are
	      printed.	For unknown historical reasons,	a  lone	 -  option  is
	      treated specially: it clears both	the -x and -v options.

       shift [number]
	      The positional parameters	number+1, number+2 etc.	are renamed to
	      1, 2, etc.  number defaults to 1.

       test expression

       [ expression ]
	      test evaluates the expression and	returns	zero status  if	 true,
	      and  1 status if false and greater than 1	if there was an	error.
	      It is normally used as the condition command  of	if  and	 while
	      statements.  The following basic expressions are available:

	       str		    str	  has  non-zero	 length.
				    Note  that	there	is   the
				    potential  for  problems  if
				    str	turns out to be	an oper-
				    ator (e.g.,	-r) - it is gen-
				    erally better to use a  test
						  [  X"str" != X
					   instead	 (double
					   quotes  are	used  in
					   case	  str	contains
					   spaces  or file glob-
					   ing characters).
	       -r file		    file exists	and is readable.
	       -w file		    file exists	and is writable.
	       -x file		    file  exists  and  is   exe-
	       -a file		    file exists.
	       -e file		    file exists.
	       -f file		    file is a regular file.
	       -d file		    file is a directory.
	       -c file		    file  is a character special
	       -b file		    file  is  a	 block	 special
	       -p file		    file is a named pipe.
	       -u file		    file's  mode  has setuid bit
	       -g file		    file's mode	has  setgid  bit
	       -k file		    file's  mode  has sticky bit
	       -s file		    file is not	empty.
	       -O file		    file's owner is the	 shell's
				    effective user-ID.
	       -G file		    file's  group is the shell's
				    effective group-ID.
	       -h file		    file is a symbolic link.
	       -H file		    file is a context  dependent
				    directory  (only  useful  on
	       -L file		    file is a symbolic link.
	       -S file		    file is a socket.
	       -o option	    shell option is set	(see set
				    command  above  for	 list of
				    options).  As a non-standard
				    extension,	 if  the  option
				    starts with	a !, the test is
				    negated;   the  test  always
				    fails  if	option	 doesn't
				    exist (thus
						  [ -o foo -o -o
						  !foo ]
					   returns true	 if  and
					   only	 if  option  foo
	       file -nt	file	    first  file	 is  newer  than
				    second  file  or  first file
				    exists and the  second  file
				    does not.
	       file -ot	file	    first  file	 is  older  than
				    second file	or  second  file
				    exists  and	 the  first file
				    does not.
	       file -ef	file	    first file is the same  file
				    as second file.

	       -t [fd]		    file  descriptor  is  a  tty
				    device.  If	the posix option
				    (set  -o  posix,  see  POSIX
				    Mode above)	is not	set,  fd
				    may	 be  left  out,	in which
				    case it is	taken  to  be  1
				    (the  behaviour  differs due
				    to the special  POSIX  rules
				    described below).
	       string		    string is not empty.
	       -z string	    string is empty.
	       -n string	    string is not empty.
	       string =	string	    strings are	equal.
	       string == string	    strings are	equal.
	       string != string	    strings are	not equal.
	       number -eq number    numbers compare equal.
	       number -ne number    numbers compare not	equal.
	       number -ge number    numbers compare greater than
				    or equal.
	       number -gt number    numbers   compare	 greater
	       number -le number    numbers compare less than or
	       number -lt number    numbers compare less than.

	      The above	basic  expressions,  in	 which	unary  operators  have
	      precedence  over binary operators, may be	combined with the fol-
	      lowing operators (listed in increasing order of precedence):

	       expr -o expr    logical or
	       expr -a expr    logical and
	       ! expr	       logical not
	       ( expr )	       grouping

	      On operating systems not supporting /dev/fd/n devices  (where  n
	      is  a  file descriptor number), the test command will attempt to
	      fake it for all tests that  operate  on  files  (except  the  -e
	      test).   I.e.,  [	 -w  /dev/fd/2 ] tests if file descriptor 2 is

	      Note that	some special rules are applied (courtesy of POSIX)  if
	      the number of arguments to test or [ ... ] is less than five: if
	      leading !	arguments can be stripped such that only one  argument
	      remains  then  a string length test is performed (again, even if
	      the argument is a	unary operator); if leading ! arguments	can be
	      stripped	such  that three arguments remain and the second argu-
	      ment is a	binary operator, then the  binary  operation  is  per-
	      formed (even if first argument is	a unary	operator, including an
	      unstripped !).

	      Note: A common mistake is	to use if [ $foo = bar ]  which	 fails
	      if  parameter  foo  is  null or unset, if	it has embedded	spaces
	      (i.e., IFS characters), or if it is a unary operator like	 !  or
	      -n.  Use tests like if [ "X$foo" = Xbar ]	instead.

       time [-p] [ pipeline ]
	      If  a  pipeline is given,	the times used to execute the pipeline
	      are reported.  If	no pipeline is given, then the user and	system
	      time  used  by the shell itself, and all the commands it has run
	      since it was started, are	reported.  The times reported are  the
	      real time	(elapsed time from start to finish), the user cpu time
	      (time spent running in user mode)	and the	system cpu time	 (time
	      spent  running  in kernel	mode).	Times are reported to standard
	      error; the format	of the output is:
		  0.00s	real	 0.00s user	0.00s system
	      unless the -p option is given (only possible if  pipeline	 is  a
	      simple command), in which	case the output	is slightly longer:
		  real	 0.00
		  user	 0.00
		  sys	 0.00
	      (the  number of digits after the decimal may vary	from system to
	      system).	Note that simple redirections of standard error	do not
	      effect the output	of the time command:
				   time	sleep 1	2> afile
				 { time	sleep 1; } 2> afile
	      times for	the first command do not go to afile, but those	of the
	      second command do.

       times  Print the	accumulated user and system times used	by  the	 shell
	      and by processes which have exited that the shell	started.

       trap [handler signal ...]
	      Sets  trap handler that is to be executed	when any of the	speci-
	      fied signals are received.  Handler is  either  a	 null  string,
	      indicating  the signals are to be	ignored, a minus (-), indicat-
	      ing that the default action is to	be taken for the signals  (see
	      signal(2	or  3)),  or  a	string containing shell	commands to be
	      evaluated	and executed at	the first opportunity (i.e., when  the
	      current  command	completes,  or	before	printing  the next PS1
	      prompt) after receipt of one of the signals.  Signal is the name
	      of  a  signal  (e.g.,  PIPE or ALRM) or the number of the	signal
	      (see kill	-l command above).  There  are	two  special  signals:
	      EXIT  (also  known  as  0),  which is executed when the shell is
	      about to exit, and ERR which is executed after an	 error	occurs
	      (an error	is something that would	cause the shell	to exit	if the
	      -e or errexit option were	set -- see set command	above).	  EXIT
	      handlers	are  executed  in the environment of the last executed
	      command.	Note that for non-interactive shells, the trap handler
	      cannot  be  changed for signals that were	ignored	when the shell

	      With no arguments, trap lists, as	a series of trap commands, the
	      current  state  of  the traps that have been set since the shell
	      started.	Note that the output of	trap can not be	usefully piped
	      to  another  process  (an	 artifact  of  the fact	that traps are
	      cleared when subprocesses	are created).

	      The original Korn	shell's	DEBUG trap and the handling of ERR and
	      EXIT traps in functions are not yet implemented.

       true   A	command	that exits with	a zero value.

       typeset	[[+-Ulprtux]  [-L[n]]  [-R[n]]	[-Z[n]]	 [-i[n]]  | -f [-tux]]
       [name[=value] ...]
	      Display  or  set	parameter attributes.  With no name arguments,
	      parameter	attributes are displayed: if no	options	arg used,  the
	      current attributes of all	parameters are printed as typeset com-
	      mands; if	an option is given (or - with no  option  letter)  all
	      parameters  and  their  values with the specified	attributes are
	      printed; if options are introduced with +, parameter values  are
	      not printed.

	      If name arguments	are given, the attributes of the named parame-
	      ters are set (-) or cleared  (+).	  Values  for  parameters  may
	      optionally  be specified.	 If typeset is used inside a function,
	      any newly	created	parameters are local to	the function.

	      When -f is used, typeset operates	on  the	 attributes  of	 func-
	      tions.  As with parameters, if no	names are given, functions are
	      listed with their	values (i.e., definitions) unless options  are
	      introduced  with	+,  in	which case only	the function names are

	       -Ln		 Left justify attribute: n specifies the field
				 width.	  If  n	 is not	specified, the current
				 width of a parameter (or  the	width  of  its
				 first assigned	value) is used.	 Leading white
				 space (and zeros, if used with	the -Z option)
				 is stripped.  If necessary, values are	either
				 truncated or space padded to  fit  the	 field

	       -Rn		 Right	justify	 attribute:  n	specifies  the
				 field width.  If n is not specified, the cur-
				 rent  width  of  a parameter (or the width of
				 its first assigned value) is used.   Trailing
				 white space are stripped.  If necessary, val-
				 ues are either	stripped of leading characters
				 or  space  padded  to make them fit the field
	       -Zn		 Zero fill attribute: if not combined with -L,
				 this  is  the same as -R, except zero padding
				 is used instead of space padding.
	       -in		 integer attribute: n specifies	 the  base  to
				 use when displaying the integer (if not spec-
				 ified,	the base given in the first assignment
				 is used).  Parameters with this attribute may
				 be  assigned  values  containing   arithmetic
	       -U		 unsigned   integer  attribute:	 integers  are
				 printed as unsigned values (only useful  when
				 combined with the -i option).	This option is
				 not in	the original Korn shell.
	       -f		 Function mode:	display	or set	functions  and
				 their attributes, instead of parameters.
	       -l		 Lower case attribute: all  upper case charac-
				 ters in values	are converted to  lower	 case.
				 (In  the  original Korn shell,	this parameter
				 meant `long integer' when used	 with  the  -i
	       -p		 Print	complete  typeset commands that	can be
				 used to re-create the attributes (but not the
				 values)  of  parameters.  This	is the default
				 action	(option	exists for  ksh93  compatabil-
	       -r		 Readonly  attribute: parameters with the this
				 attribute may not be assigned	to  or	unset.
				 Once  this  attribute	is  set, it can	not be
				 turned	off.
	       -t		 Tag attribute:	has no meaning to  the	shell;
				 provided for application use.

				 For  functions,  -t  is  the trace attribute.
				 When functions	with the trace	attribute  are
				 executed,  the	 xtrace	 (-x)  shell option is
				 temporarily turned on.
	       -u		 Upper case attribute: all lower case  charac-
				 ters  in  values are converted	to upper case.
				 (In the original Korn shell,  this  parameter
				 meant	`unsigned  integer' when used with the
				 -i option, which  meant  upper	 case  letters
				 would	never  be  used	for bases greater than
				 10.  See the -U option).

				 For functions,	-u is the undefined attribute.
				 See  Functions	 above for the implications of
	       -x		 Export	attribute: parameters  (or  functions)
				 are placed in the environment of any executed
				 commands.  Exported functions are not	imple-
				 mented	yet.

       ulimit [-acdfHlmnpsStvw]	[value]
	      Display or set process limits.  If no options are	used, the file
	      size limit (-f) is assumed.  value, if specified,	may be	either
	      be  an  arithmetic expression or the word	unlimited.  The	limits
	      affect the shell and any processes created by the	shell after  a
	      limit  is	 imposed.  Note	that some systems may not allow	limits
	      to be increased once they	are set.  Also note that the types  of
	      limits  available	 are system dependent -	some systems have only
	      the -f limit.

	      -a     Displays all limits; unless -H is used, soft  limits  are

	      -H     Set  the hard limit only (default is to set both hard and
		     soft limits).

	      -S     Set the soft limit	only (default is to set	both hard  and
		     soft limits).

	      -c     Impose  a	size  limit  of	 n  blocks on the size of core

	      -d     Impose a size limit of n kbytes on	the size of  the  data

	      -f     Impose  a	size limit of n	blocks on files	written	by the
		     shell and its child processes (files of any size  may  be

	      -l     Impose  a	limit  of  n  kbytes  on  the amount of	locked
		     (wired) physical memory.

	      -m     Impose a limit of n kbytes	on the amount of physical mem-
		     ory used.

	      -n     Impose  a limit of	n file descriptors that	can be open at

	      -p     Impose a limit of n processes that	can be run by the user
		     at	any one	time.

	      -s     Impose  a size limit of n kbytes on the size of the stack

	      -t     Impose a time limit of n cpu seconds to be	used  by  each

	      -v     Impose  a limit of	n kbytes on the	amount of virtual mem-
		     ory used; on some systems this is the  maximum  allowable
		     virtual address (in bytes,	not kbytes).

	      -w     Impose  a	limit  of n kbytes on the amount of swap space

	      As far as	ulimit is concerned, a block is	512 bytes.

       umask [-S] [mask]
	      Display or set the file permission creation mask,	or umask  (see
	      umask(2)).   If the -S option is used, the mask displayed	or set
	      is symbolic, otherwise it	is an octal number.

	      Symbolic masks are like those used by chmod(1):
	      in which the first group of characters is	the who	part, the sec-
	      ond  group  is the op part, and the last group is	the perm part.
	      The who part specifies which part	of the umask is	 to  be	 modi-
	      fied.  The letters mean:

		     u	    the	user permissions

		     g	    the	group permissions

		     o	    the	other permissions (non-user, non-group)

		     a	    all	permissions (user, group and other)

	      The  op  part  indicates how the who permissions are to be modi-

		     =	    set

		     +	    added to

		     -	    removed from

	      The perm part specifies which permissions	are to be  set,	 added
	      or removed:

		     r	    read permission

		     w	    write permission

		     x	    execute permission

	      When symbolic masks are used, they describe what permissions may
	      be made available	(as opposed to octal masks in which a set  bit
	      means  the  corresponding	 bit  is  to  be  cleared).   Example:
	      `ug=rwx,o=' sets	the  mask  so  files  will  not	 be  readable,
	      writable	or  executable by `others', and	is equivalent (on most
	      systems) to the octal mask `07'.

       unalias [-adt] [name1 ...]
	      The aliases for the given	names are removed.  If the  -a	option
	      is  used,	 all aliases are removed.  If the -t or	-d options are
	      used, the	indicated operations are carried  out  on  tracked  or
	      directory	aliases, respectively.

       unset [-fv] parameter ...
	      Unset  the named parameters (-v, the default) or functions (-f).
	      The exit status is  non-zero  if	any  of	 the  parameters  were
	      already unset, zero otherwise.

       wait [job]
	      Wait  for	 the  specified	 job(s)	to finish.  The	exit status of
	      wait is that of the last specified  job:	if  the	 last  job  is
	      killed  by  a signal, the	exit status is 128 + the number	of the
	      signal (see kill -l exit-status above); if  the  last  specified
	      job  can't  be  found  (because it never existed,	or had already
	      finished), the exit status of wait  is  127.   See  Job  Control
	      below  for  the format of	job.  Wait will	return if a signal for
	      which a trap has been set	is received, or	if a HUP, INT or  QUIT
	      signal is	received.

	      If  no  jobs are specified, wait waits for all currently running
	      jobs (if any) to finish and exits	with a zero  status.   If  job
	      monitoring  is enabled, the completion status of jobs is printed
	      (this is not the case when jobs are explicitly specified).

       whence [-pv] [name ...]
	      For each name, the type of command  is  listed  (reserved	 word,
	      built-in,	alias, function, tracked alias or executable).	If the
	      -p option	is used, a path	search done even if name is a reserved
	      word,  alias,  etc.  Without the -v option, whence is similar to
	      command -v except	that whence will find reserved words and won't
	      print  aliases  as alias commands; with the -v option, whence is
	      the same as command -V.  Note that for  whence,  the  -p	option
	      does  not	 affect	 the search path used, as it does for command.
	      If the type of one or more of the	names could not	be determined,
	      the exit status is non-zero.

   Job Control
       Job  control refers to the shell's ability to monitor and control jobs,
       which are processes or groups of	 processes  created  for  commands  or
       pipelines.   At	a  minimum, the	shell keeps track of the status	of the
       background (i.e., asynchronous) jobs that currently exist; this	infor-
       mation  can  be	displayed  using  the jobs command.  If	job control is
       fully enabled (using set	-m or set -o monitor), as it is	 for  interac-
       tive  shells,  the  processes  of a job are placed in their own process
       group, foreground jobs can be stopped by	typing the  suspend  character
       from  the  terminal  (normally ^Z), jobs	can be restarted in either the
       foreground or background, using the fg and bg  commands,	 respectively,
       and  the	 state	of the terminal	is saved or restored when a foreground
       job is stopped or restarted, respectively.

       Note that only commands that create processes (e.g., asynchronous  com-
       mands,  subshell	commands, and non-built-in, non-function commands) can
       be stopped; commands like read cannot be.

       When a job is created, it is assigned a	job-number.   For  interactive
       shells, this number is printed inside [..], followed by the process-ids
       of the processes	in the job when	an asynchronous	command	is run.	 A job
       may  be	referred  to in	bg, fg,	jobs, kill and wait commands either by
       the process id of the last process in the command pipeline  (as	stored
       in the $! parameter) or by prefixing the	job-number with	a percent sign
       (%).  Other percent sequences can also be used to refer to jobs:

	%+			 The most recently stopped job,	or,  if	 there
				 are  no stopped jobs, the oldest running job.
	%%, %			 Same as %+.
	%-			 The job that would be	the  %+	 job,  if  the
				 later did not exist.
	%n			 The job with job-number n.
	%?string		 The  job  containing  the  string  string (an
				 error occurs if multiple jobs are matched).
	%string			 The job starting with string string (an error
				 occurs	if multiple jobs are matched).

       When a job changes state	(e.g., a background job	finishes or foreground
       job is stopped),	the shell prints the following status information:
	      [number] flag status command

	      is the job-number	of the job.

	flag  is + or -	if the job is the %+ or	%- job,	respectively, or space
	      if it is neither.

	      indicates	the current state of the job and can be

		     the  job has neither stopped or exited (note that running
		     does not necessarily  mean	 consuming  CPU	 time  --  the
		     process could be blocked waiting for some event).

	      Done [(number)]
		     the  job  exited.	number	is the exit status of the job,
		     which is omitted if the status is zero.

	      Stopped [(signal)]
		     the job was stopped by the	indicated signal (if no	signal
		     is	given, the job was stopped by SIGTSTP).

	      signal-description [(core	dumped)]
		     the  job  was  killed  by	a  signal (e.g., Memory	fault,
		     Hangup, etc. -- use kill -l for a list of signal descrip-
		     tions).   The (core dumped) message indicates the process
		     created a core file.

	      is the command that created the process.	If there are  multiple
	      processes	in the job, then each process will have	a line showing
	      its command and possibly its status, if it is different from the
	      status of	the previous process.

       When  an	 attempt is made to exit the shell while there are jobs	in the
       stopped state, the shell	warns the user that there are stopped jobs and
       does  not  exit.	  If  another  attempt is immediately made to exit the
       shell, the stopped jobs are sent	a HUP  signal  and  the	 shell	exits.
       Similarly,  if  the  nohup option is not	set and	there are running jobs
       when an attempt is made to exit a login shell, the shell	warns the user
       and  does not exit.  If another attempt is immediately made to exit the
       shell, the running jobs are sent	a HUP signal and the shell exits.

   Interactive Input Line Editing
       The shell supports three	modes of reading command lines from a  tty  in
       an  interactive	session.   Which  is  used is controlled by the	emacs,
       gmacs and vi set	options	(at most one of	these can be set at once).  If
       none  of	 these	options	is enabled, the	shell simply reads lines using
       the normal tty driver.  If the emacs or gmacs option is set, the	 shell
       allows  emacs  like editing of the command; similarly, if the vi	option
       is set, the shell allows	vi like	editing	of the command.	  These	 modes
       are described in	detail in the following	sections.

       In  these editing modes,	if a line is longer that the screen width (see
       COLUMNS parameter), a >,	+ or < character is displayed in the last col-
       umn  indicating that there are more characters after, before and	after,
       or before the current position, respectively.   The  line  is  scrolled
       horizontally as necessary.

   Emacs Editing Mode
       When  the  emacs	 option	 is  set,  interactive	input  line editing is
       enabled.	 Warning: This mode is slightly	different from the emacs  mode
       in  the	original Korn shell and	the 8th	bit is stripped	in emacs mode.
       In this mode various editing commands (typically	bound to one  or  more
       control	characters) cause immediate actions without waiting for	a new-
       line.  Several editing commands are bound to particular control charac-
       ters when the shell is invoked; these bindings can be changed using the
       following commands:

       bind   The current bindings are listed.

       bind string=[editing-command]
	      The specified editing command is	bound  to  the	given  string,
	      which  should consist of a control character (which may be writ-
	      ten using	caret notation ^X), optionally preceded	by one of  the
	      two  prefix  characters.	 Future	input of the string will cause
	      the editing  command  to	be  immediately	 invoked.   Note  that
	      although	only  two  prefix  characters (usually ESC and ^X) are
	      supported, some multi-character sequences	can be supported.  The
	      following	 binds	the  arrow  keys on an ANSI terminal, or xterm
	      (these are in the	default	 bindings).   Of  course  some	escape
	      sequences	won't work out quite this nicely:

	      bind '^[['=prefix-2
	      bind '^XA'=up-history
	      bind '^XB'=down-history
	      bind '^XC'=forward-char
	      bind '^XD'=backward-char

       bind -l
	      Lists the	names of the functions to which	keys may be bound.

       bind -m string=[substitute]
	      The  specified  input  string  will  afterwards  be  immediately
	      replaced by the given substitute string, which may contain edit-
	      ing commands.

       The  following  is a list of editing commands available.	 Each descrip-
       tion starts with	the name of the	command, a n, if the  command  can  be
       prefixed	 with a	count, and any keys the	command	is bound to by default
       (written	using caret notation, e.g., ASCII ESC character	is written  as
       ^[).   A	 count prefix for a command is entered using the sequence ^[n,
       where n is a sequence of	1 or more digits; unless otherwise  specified,
       if  a  count  is	 omitted, it defaults to 1.  Note that editing command
       names are used only with	the bind command.  Furthermore,	 many  editing
       commands	 are  useful  only  on	terminals  with	a visible cursor.  The
       default bindings	were chosen to resemble	corresponding EMACS key	 bind-
       ings.   The  users tty characters (e.g.,	ERASE) are bound to reasonable
       substitutes and override	the default bindings.

       abort ^G
	      Useful as	a response to a	request	for a  search-history  pattern
	      in order to abort	the search.

       auto-insert n
	      Simply  causes  the  character to	appear as literal input.  Most
	      ordinary characters are bound to this.

       backward-char  n	^B
	      Moves the	cursor backward	n characters.

       backward-word  n	^[B
	      Moves the	cursor backward	to the beginning of a word; words con-
	      sist of alphanumerics, underscore	(_) and	dollar ($).

       beginning-of-history ^[<
	      Moves to the beginning of	the history.

       beginning-of-line ^A
	      Moves the	cursor to the beginning	of the edited input line.

       capitalize-word n ^[c, ^[C
	      Uppercase	 the  first character in the next n words, leaving the
	      cursor past the end of the last word.  If	the current line  does
	      not  begin  with a comment character, one	is added at the	begin-
	      ning of the line and the line is entered (as if return had  been
	      pressed),	 otherwise the existing	comment	characters are removed
	      and the cursor is	placed at the beginning	of the line.

       complete	^[^[
	      Automatically completes as much as is unique of the command name
	      or the file name containing the cursor.  If the entire remaining
	      command or file name is unique a space is	printed	after its com-
	      pletion,	unless	it  is	a  directory  name  in which case / is
	      appended.	 If there is no	command	or file	name with the  current
	      partial  word as its prefix, a bell character is output (usually
	      causing a	audio beep).

       complete-command	^X^[
	      Automatically completes as much as is unique of the command name
	      having  the  partial  word up to the cursor as its prefix, as in
	      the complete command described above.

       complete-file ^[^X
	      Automatically completes as much as is unique of  the  file  name
	      having  the  partial  word up to the cursor as its prefix, as in
	      the complete command described above.

       complete-list ^[=
	      List the possible	completions for	the current word.

       delete-char-backward n ERASE, ^?, ^H
	      Deletes n	characters before the cursor.

       delete-char-forward n
	      Deletes n	characters after the cursor.

       delete-word-backward n ^[ERASE, ^[^?, ^[^H, ^[h
	      Deletes n	words before the cursor.

       delete-word-forward n ^[d
	      Deletes characters after the cursor up to	the end	of n words.

       down-history n ^N
	      Scrolls the history buffer forward n lines (later).  Each	 input
	      line  originally starts just after the last entry	in the history
	      buffer, so down-history is not useful until  either  search-his-
	      tory or up-history has been performed.

       downcase-word n ^[L, ^[l
	      Lowercases the next n words.

       end-of-history ^[>
	      Moves to the end of the history.

       end-of-line ^E
	      Moves the	cursor to the end of the input line.

       eot ^_ Acts  as	an end-of-file;	this is	useful because edit-mode input
	      disables normal terminal input canonicalization.

       eot-or-delete n ^D
	      Acts as eot if alone on a	line; otherwise	acts  as  delete-char-

       error  Error (ring the bell).

       exchange-point-and-mark ^X^X
	      Places  the cursor where the mark	is, and	sets the mark to where
	      the cursor was.

       expand-file ^[*
	      Appends a	* to the current word and replaces the word  with  the
	      result  of  performing  file  globbing on	the word.  If no files
	      match the	pattern, the bell is rung.

       forward-char n ^F
	      Moves the	cursor forward n characters.

       forward-word n ^[f
	      Moves the	cursor forward to the end of the nth word.

       goto-history n ^[g
	      Goes to history number n.

       kill-line KILL
	      Deletes the entire input line.

       kill-region ^W
	      Deletes the input	between	the cursor and the mark.

       kill-to-eol n ^K
	      Deletes the input	from the cursor	to the end of the line if n is
	      not  specified,  otherwise deletes characters between the	cursor
	      and column n.

       list ^[?
	      Prints a sorted, columnated list of command names	or file	 names
	      (if  any)	that can complete the partial word containing the cur-
	      sor.  Directory names have / appended to them.

       list-command ^X?
	      Prints a sorted, columnated list of command names	(if any)  that
	      can complete the partial word containing the cursor.

       list-file ^X^Y
	      Prints a sorted, columnated list of file names (if any) that can
	      complete the partial word	 containing  the  cursor.   File  type
	      indicators are appended as described under list above.

       newline ^J, ^M
	      Causes the current input line to be processed by the shell.  The
	      current cursor position may be anywhere on the line.

       newline-and-next	^O
	      Causes the current input line to be processed by the shell,  and
	      the  next	 line  from history becomes the	current	line.  This is
	      only useful after	an up-history or search-history.

       no-op QUIT
	      This does	nothing.

       prefix-1	^[
	      Introduces a 2-character command sequence.

       prefix-2	^X

       prefix-2	^[[
	      Introduces a 2-character command sequence.

       prev-hist-word n	^[., ^[_
	      The last (nth) word of the previous command is inserted  at  the

       quote ^^
	      The  following  character	 is  taken literally rather than as an
	      editing command.

       redraw ^L
	      Reprints the prompt string and the current input line.

       search-character-backward n ^[^]
	      Search backward in the current line for the nth occurance	of the
	      next character typed.

       search-character-forward	n ^]
	      Search  forward in the current line for the nth occurance	of the
	      next character typed.

       search-history ^R
	      Enter incremental	search mode.  The  internal  history  list  is
	      searched	backwards for commands matching	the input.  An initial
	      ^	in the search string anchors the search.  The abort  key  will
	      leave  search mode.  Other commands will be executed after leav-
	      ing search mode.	Successive  search-history  commands  continue
	      searching	 backward  to the next previous	occurrence of the pat-
	      tern.  The history buffer	retains	only a finite number of	lines;
	      the oldest are discarded as necessary.

       set-mark-command	^[<space>
	      Set the mark at the cursor position.

       stuff  On  systems  supporting it, pushes the bound character back onto
	      the terminal input where it may receive  special	processing  by
	      the terminal handler.  This is useful for	the BRL	^T mini-systat
	      feature, for example.

	      Acts like	stuff, then aborts input the same as an	interrupt.

       transpose-chars ^T
	      If at the	end of line, or	if  the	 gmacs	option	is  set,  this
	      exchanges	 the  two previous characters; otherwise, it exchanges
	      the previous and current characters and  moves  the  cursor  one
	      character	to the right.

       up-history n ^P
	      Scrolls the history buffer backward n lines (earlier).

       upcase-word n ^[U, ^[u
	      Uppercases the next n words.

       version ^V
	      Display the version of ksh.  The current edit buffer is restored
	      as soon as any key is pressed (the key is	then processed,	unless
	      it is a space).

       yank ^Y
	      Inserts the most recently	killed text string at the current cur-
	      sor position.

       yank-pop	^[y
	      Immediately after	a yank,	replaces the inserted text string with
	      the next previous	killed text string.

   Vi Editing Mode
       The  vi	command	 line editor in	ksh has	basically the same commands as
       the vi editor (see vi(1)), with the following exceptions:

	 o    you start	out in insert mode,

	 o    there are	file name and command completion commands  (=,	\,  *,
	      ^X, ^E, ^F and, optionally, <tab>),

	 o    the  _ command is	different (in ksh it is	the last argument com-
	      mand, in vi it goes to the start of the current line),

	 o    the / and	G commands move	in the opposite	 direction  as	the  j

	 o    and  commands which don't	make sense in a	single line editor are
	      not available (e.g., screen movement commands,  ex  :  commands,

       Note  that  the	^X stands for control-X; also <esc>, <space> and <tab>
       are used	for escape, space and tab, respectively	(no kidding).

       Like vi,	there are two modes: insert mode and command mode.  In	insert
       mode,  most characters are simply put in	the buffer at the current cur-
       sor position as they are	typed, however,	some  characters  are  treated
       specially.  In particular, the following	characters are taken from cur-
       rent tty	settings (see stty(1)) and have	their  usual  meaning  (normal
       values  are  in	parentheses):  kill (^U), erase	(^?), werase (^W), eof
       (^D), intr (^C) and quit	(^\).  In addition to the above, the following
       characters are also treated specially in	insert mode:

	^H			 erases	previous character
	^V			 literal next: the next	character typed	is not
				 treated specially (can	be used	to insert  the
				 characters being described here)
	^J ^M			 end of	line: the current line is read,	parsed
				 and executed by the shell
	<esc>			 puts the editor in command mode (see below)
	^E			 command and file name enumeration (see	below)
	^F			 command and file name completion (see below).
				 If used twice in a row, the list of  possible
				 completions  is  displayed;  if  used a third
				 time, the completion is undone.
	^X			 command and file name expansion (see below)

	<tab>			 optional file	name  and  command  completion
				 (see  ^F  above), enabled with	set -o vi-tab-

       In command mode,	each character is interpreted as a  command.   Charac-
       ters  that  don't  correspond  to commands, are illegal combinations of
       commands	or are commands	that can't be carried out all cause beeps.  In
       the  following  command	descriptions, a	n indicates the	command	may be
       prefixed	by a number (e.g., 10l moves right 10 characters); if no  num-
       ber  prefix  is	used, n	is assumed to be 1 unless otherwise specified.
       The term	`current position' refers to the position between  the	cursor
       and the character preceding the cursor.	A `word' is a sequence of let-
       ters, digits and	underscore characters or  a  sequence  of  non-letter,
       non-digit,  non-underscore,  non-white-space  characters	 (e.g.,	ab2*&^
       contains	two words) and a `big-word' is a sequence  of  non-white-space

       Special ksh vi commands
	      The  following  commands	are not	in, or are different from, the
	      normal vi	file editor:

	      n_     insert a space followed by	the nth	big-word from the last
		     command  in the history at	the current position and enter
		     insert mode; if n is not  specified,  the	last  word  is

	      #	     insert the	comment	character (#) at the start of the cur-
		     rent line and return the line to the shell	(equivalent to

	      ng     like G, except if n is not	specified, it goes to the most
		     recent remembered line.

	      nv     edit line n using the vi editor; if n is  not  specified,
		     the  current line is edited.  The actual command executed
		     is	`fc -e ${VISUAL:-${EDITOR:-vi}}	n'.

	      *	and ^X
		     command or	file name expansion is applied to the  current
		     big-word  (with  an  appended  *, if the word contains no
		     file globing characters) -	the big-word is	replaced  with
		     the  resulting  words.   If  the  current big-word	is the
		     first on the line (or follows one of the following	 char-
		     acters:  ;,  |, &,	(, )) and does not contain a slash (/)
		     then command  expansion  is  done,	 otherwise  file  name
		     expansion is done.	 Command expansion will	match the big-
		     word against all aliases, functions and built-in commands
		     as	 well  as  any executable files	found by searching the
		     directories in the	PATH parameter.	 File  name  expansion
		     matches  the  big-word  against  the files	in the current
		     directory.	 After expansion, the cursor  is  placed  just
		     past the last word	and the	editor is in insert mode.

	      n\, n^F, n<tab> and n<esc>
		     command/file  name	 completion:  replace the current big-
		     word with the longest unique match	 obtained  after  per-
		     forming  command/file name	expansion.  <tab> is only rec-
		     ognized if	the vi-tabcomplete option is set, while	 <esc>
		     is	 only  recognized  if the vi-esccomplete option	is set
		     (see set -o).  If n is specified, the nth	possible  com-
		     pletion is	selected (as reported by the command/file name
		     enumeration command).

	      =	and ^E
		     command/file name enumeration: list all the  commands  or
		     files that	match the current big-word.

	      ^V     display  the  version  of	pdksh;	it  is displayed until
		     another key is pressed (this key is ignored).

	      @c     macro expansion: execute the commands found in the	 alias

       Intra-line movement commands

	      nh and n^H
		     move left n characters.

	      nl and n<space>
		     move right	n characters.

	      0	     move to column 0.

	      ^	     move to the first non white-space character.

	      n|     move to column n.

	      $	     move to the last character.

	      nb     move back n words.

	      nB     move back n big-words.

	      ne     move forward to the end the word, n times.

	      nE     move forward to the end the big-word, n times.

	      nw     move forward n words.

	      nW     move forward n big-words.

	      %	     find  match:  the	editor	looks  forward for the nearest
		     parenthesis, bracket or brace and then moves the  to  the
		     matching parenthesis, bracket or brace.

	      nfc    move forward to the nth occurrence	of the character c.

	      nFc    move backward to the nth occurrence of the	character c.

	      ntc    move  forward  to	just  before the nth occurrence	of the
		     character c.

	      nTc    move backward to just before the nth  occurrence  of  the
		     character c.

	      n;     repeats the last f, F, t or T command.

	      n,     repeats  the  last	f, F, t	or T command, but moves	in the
		     opposite direction.

       Inter-line movement commands

	      nj and n+	and n^N
		     move to the nth next line in the history.

	      nk and n-	and n^P
		     move to the nth previous line in the history.

	      nG     move to line n in the history; if n is not	specified, the
		     number first remembered line is used.

	      ng     like G, except if n is not	specified, it goes to the most
		     recent remembered line.

		     search backward through the history for the nth line con-
		     taining string; if	string starts with ^, the remainder of
		     the string	must appear at the start of the	 history  line
		     for it to match.

		     same  as  /,  except it searches forward through the his-

	      nn     search for	the nth	occurrence of the last search  string;
		     the  direction  of	 the  search  is  the same as the last

	      nN     search for	the nth	occurrence of the last search  string;
		     the  direction  of	the search is the opposite of the last

       Edit commands

	      na     append text n times: goes into insert mode	just after the
		     current  position.	 The append is only replicated if com-
		     mand mode is re-entered (i.e., <esc> is used).

	      nA     same as a,	except it appends at the end of	the line.

	      ni     insert text n times: goes into insert mode	at the current
		     position.	 The  insertion	 is only replicated if command
		     mode is re-entered	(i.e., <esc> is	used).

	      nI     same as i,	except the insertion is	done just  before  the
		     first non-blank character.

	      ns     substitute	 the next n characters (i.e., delete the char-
		     acters and	go into	insert mode).

	      S	     substitute	whole line: all	characters from	the first non-
		     blank character to	the end	of line	are deleted and	insert
		     mode is entered.

		     change from the current position to the position  result-
		     ing  from	n move-cmds (i.e., delete the indicated	region
		     and go into insert	mode); if  move-cmd  is	 c,  the  line
		     starting from the first non-blank character is changed.

	      C	     change  from  the current position	to the end of the line
		     (i.e., delete to the end of the line and go  into	insert

	      nx     delete the	next n characters.

	      nX     delete the	previous n characters.

	      D	     delete to the end of the line.

		     delete  from the current position to the position result-
		     ing from n	move-cmds; move-cmd is a movement command (see
		     above) or d, in which case	the current line is deleted.

	      nrc    replace the next n	characters with	the character c.

	      nR     replace: enter insert mode	but overwrite existing charac-
		     ters instead of  inserting	 before	 existing  characters.
		     The replacement is	repeated n times.

	      n~     change the	case of	the next n characters.

		     yank  from	the current position to	the position resulting
		     from n move-cmds into the yank buffer; if move-cmd	is  y,
		     the whole line is yanked.

	      Y	     yank from the current position to the end of the line.

	      np     paste the contents	of the yank buffer just	after the cur-
		     rent position, n times.

	      nP     same as p,	except the buffer is  pasted  at  the  current

       Miscellaneous vi	commands

	      ^J and ^M
		     the  current  line	 is  read,  parsed and executed	by the

	      ^L and ^R
		     redraw the	current	line.

	      n.     redo the last edit	command	n times.

	      u	     undo the last edit	command.

	      U	     undo all changes that have	been made to the current line.

	      intr and quit
		     the interrupt and quit terminal characters	cause the cur-
		     rent line to be deleted and a new prompt to be printed.


       Any bugs	in  pdksh  should  be  reported	 to	Please
       include the version of pdksh (echo $KSH_VERSION shows it), the machine,
       operating system	and compiler you are using and a description of	how to
       repeat  the  bug	 (a  small  shell  script that demonstrates the	bug is
       best).  The following, if relevant (if you are not sure,	include	them),
       can also	helpful: options you are using (both options.h options and set
       -o options) and a copy of your config.h (the file generated by the con-
       figure	script).    New	  versions  of	pdksh  can  be	obtained  from

       BTW, the	most frequently	reported bug is
	       echo hi | read a; echo $a   # Does not print hi
       I'm aware of this and there is no need to report	it.

       This page documents version
			    @(#)PD KSH v5.2.14 99/07/13.2
       of the public domain korn shell.

       This shell is based on the public domain	7th edition Bourne shell clone
       by  Charles  Forsyth  and  parts	of the BRL shell by Doug A. Gwyn, Doug
       Kingston, Ron Natalie, Arnold Robbins, Lou  Salkind  and	 others.   The
       first  release  of  pdksh  was created by Eric Gisin, and it was	subse-
       quently maintained by John R.  MacMillan	 (chance!,  and
       Simon  J.  Gerraty  (   The	current	 maintainer is
       Michael Rendell (   The  CONTRIBUTORS	 file  in  the
       source  distribution  contains a	more complete list of people and their
       part in the shell's development.

       awk(1), sh(1), csh(1), ed(1), getconf(1), getopt(1),  sed(1),  stty(1),
       vi(1),  dup(2),	execve(2),  getgid(2),	getuid(2),  open(2),  pipe(2),
       wait(2),	getopt(3), rand(3), signal(3), system(3), environ(5)

       The KornShell Command and Programming Language, Morris Bolsky and David
       Korn, 1989, ISBN	0-13-516972-0.

       UNIX Shell Programming, Stephen G. Kochan, Patrick H. Wood, Hayden.

       IEEE  Standard  for  information	Technology - Portable Operating	System
       Interface (POSIX) - Part	2: Shell and Utilities,	IEEE Inc,  1993,  ISBN

				August 19, 1996				KSH(1)


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