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sh(1)				 User Commands				 sh(1)

       sh, jsh - standard and job control shell	and command interpreter

       /usr/bin/sh [-acefhiknprstuvx] [argument...]

       /usr/xpg4/bin/sh	[ +- abCefhikmnoprstuvx] [ +- o	option...] [-c string]

       /usr/bin/jsh [-acefhiknprstuvx] [argument...]

       The /usr/bin/sh utility is a command programming	language that executes
       commands	read from a terminal or	a file.

       The /usr/xpg4/bin/sh utility is a standards compliant shell. This util-
       ity provides all	the functionality of ksh(1), except in cases discussed
       in ksh(1) where differences in behavior exist.

       The  jsh	 utility is an interface to the	shell that provides all	of the
       functionality of	sh and enables job control (see	 Job  Control  section

       Arguments to the	shell are listed in the	Invocation section below.

       A  blank	 is  a	tab or a space.	A name is a sequence of	ASCII letters,
       digits, or underscores, beginning with a	letter or an underscore. A pa-
       rameter	is a name, a digit, or any of the characters *,	@, #, ?, -, $,
       and !.

       A simple-command	is a sequence of non-blank words separated by  blanks.
       The first word specifies	the name of the	command	to be executed.	Except
       as specified below, the remaining words are passed as arguments to  the
       invoked	command.  The  command	name  is  passed  as  argument	0 (see
       exec(2)). The value of a	simple-command is its exit status if it	termi-
       nates  normally,	or (octal) 200+status if it terminates abnormally. See
       signal.h(3HEAD) for a list of status values.

       A pipeline is a sequence	of one or more commands	separated  by  |.  The
       standard	 output	of each	command	but the	last is	connected by a pipe(2)
       to the standard input of	the next command. Each command	is  run	 as  a
       separate	 process.  The	shell waits for	the last command to terminate.
       The exit	status of a pipeline is	the exit status	of the last command in
       the pipeline.

       A list is a sequence of one or more pipelines separated by ;, &,	&&, or
       ||, and optionally terminated by	; or &.	Of these four symbols, ; and &
       have  equal precedence, which is	lower than that	of && and ||. The sym-
       bols && and || also have	equal precedence. A semicolon (;)  causes  se-
       quential	 execution of the preceding pipeline, that is, the shell waits
       for the pipeline	to finish before executing any commands	following  the
       semicolon.  An  ampersand (&) causes asynchronous execution of the pre-
       ceding pipeline,	that is, the shell does	not wait for that pipeline  to
       finish.	The symbol && (||) causes the list following it	to be executed
       only if the preceding pipeline returns a	zero (non-zero)	 exit  status.
       An  arbitrary number of newlines	may appear in a	list, instead of semi-
       colons, to delimit commands.

       A command is either a simple-command or one of  the  following.	Unless
       otherwise  stated,  the value returned by a command is that of the last
       simple-command executed in the command.

       for name	[ in word ... ]	do list	done

	   Each	time a for command is executed,	name is	set to the  next  word
	   taken  from	the  in	word list. If in word ... is omitted, then the
	   for command executes	the do list once for each positional parameter
	   that	 is  set (see Parameter	Substitution section below). Execution
	   ends	when there are no more words in	the list.

       case word in [ pattern [	| pattern ] ) list ;; ]	...  esac

	   A case command executes the list associated with the	first  pattern
	   that	 matches  word.	 The  form of the patterns is the same as that
	   used	for file-name generation (see File Name	 Generation  section),
	   except  that	a slash, a leading dot,	or a dot immediately following
	   a slash need	not be matched explicitly.

       if list ; then list ; [ elif list ; then	list ; ] ... [ else list  ;  ]

       The  list  following if is executed and,	if it returns a	zero exit sta-
       tus, the	list following the first then is executed. Otherwise, the list
       following  elif is executed and,	if its value is	zero, the list follow-
       ing the next then is executed. Failing that, the	else list is executed.
       If no else list or then list is executed, then the if command returns a
       zero exit status.

       while list do list done	       A while command repeatedly executes the
				       while  list  and, if the	exit status of
				       the last	command	in the list  is	 zero,
				       executes	 the  do  list;	 otherwise the
				       loop terminates.	If no commands in  the
				       do  list	 are  executed,	then the while
				       command returns a zero exit status; un-
				       til  may	 be  used in place of while to
				       negate the loop termination test.

       (list)			       Execute list in a sub-shell.

       { list;}			       list is executed	in the	current	 (that
				       is,  parent)  shell. The	{ must be fol-
				       lowed by	a space.

       name () { list;}		       Define a	function which	is  referenced
				       by  name.  The  body of the function is
				       the list	of commands between {  and  }.
				       The { must be followed by a space. Exe-
				       cution of functions is described	 below
				       (see  Execution	section).  The { and }
				       are unnecessary	if  the	 body  of  the
				       function	is a command as	defined	above,
				       under Commands.

       The following words are only recognized as the first word of a  command
       and when	not quoted:

	if   then   else  elif	fi  case  esac	for  while  until  do  done  {

   Comments Lines
       A word beginning	with # causes that word	and all	the following  charac-
       ters up to a newline to be ignored.

   Command Substitution
       The shell reads commands	from the string	between	two grave accents (``)
       and the standard	output from these commands may be used as all or  part
       of a word. Trailing newlines from the standard output are removed.

       No  interpretation is done on the string	before the string is read, ex-
       cept to remove backslashes (\) used to escape other  characters.	 Back-
       slashes	may  be	used to	escape a grave accent (`) or another backslash
       (\) and are removed before the command string is	read.  Escaping	 grave
       accents allows nested command substitution. If the command substitution
       lies within a pair of double quotes (" ...` ...`	...  "),  a  backslash
       used  to	escape a double	quote (\") will	be removed; otherwise, it will
       be left intact.

       If a backslash is used to escape	a newline character  (\newline),  both
       the  backslash  and  the	 newline are removed (see the later section on
       Quoting). In addition, backslashes used to escape dollar	signs (\$) are
       removed.	 Since no parameter substitution is done on the	command	string
       before it is read, inserting a backslash	to escape a dollar sign	has no
       effect.	Backslashes  that  precede characters other than \, `, ", new-
       line, and $ are left intact when	the command string is read.

   Parameter Substitution
       The character $ is used to introduce  substitutable  parameters.	 There
       are  two	types of parameters, positional	and keyword. If	parameter is a
       digit, it is a positional parameter. Positional parameters may  be  as-
       signed  values by set. Keyword parameters (also known as	variables) may
       be assigned values by writing:

       name=value [ name=value ] ...

       Pattern-matching	is not performed on value. There cannot	be a  function
       and a variable with the same name.

       ${parameter}	       The  value, if any, of the parameter is substi-
			       tuted. The braces are required only when	param-
			       eter  is	followed by a letter, digit, or	under-
			       score that is not to be interpreted as part  of
			       its name. If parameter is * or @, all the posi-
			       tional parameters, starting with	$1,  are  sub-
			       stituted	(separated by spaces). Parameter $0 is
			       set from	argument zero when the	shell  is  in-

       ${parameter:-word}      If parameter is set and is non-null, substitute
			       its value; otherwise substitute word.

       ${parameter:=word}      If parameter is not set or is null  set	it  to
			       word;  the  value  of  the parameter is substi-
			       tuted. Positional parameters  may  not  be  as-
			       signed in this way.

       ${parameter:?word}      If parameter is set and is non-null, substitute
			       its value; otherwise, print word	and exit  from
			       the shell. If word is omitted, the message "pa-
			       rameter null or not set"	is printed.

       ${parameter:+word}      If parameter is set and is non-null, substitute
			       word; otherwise substitute nothing.

       In the above, word is not evaluated unless it is	to be used as the sub-
       stituted	string,	so that, in the	following  example,  pwd  is  executed
       only if d is not	set or is null:

       echo  ${d:-`pwd`}

       If  the colon (:) is omitted from the above expressions,	the shell only
       checks whether parameter	is set or not.

       The following parameters	are automatically set by the shell.

       #	       The number of positional	parameters in decimal.

       -	       Flags supplied to the shell on invocation or by the set

       ?	       The  decimal  value  returned by	the last synchronously
		       executed	command.

       $	       The process number of this shell.

       !	       The process number of the last background  command  in-

       The  following parameters are used by the shell.	The parameters in this
       section are also	referred to as environment variables.

       HOME	       The default argument (home directory) for the  cd  com-
		       mand,  set  to  the  user's login directory by login(1)
		       from the	password file (see passwd(4)).

       PATH	       The search path for commands (see Execution section be-

       CDPATH	       The search path for the cd command.

       MAIL	       If this parameter is set	to the name of a mail file and
		       the MAILPATH  parameter is not set, the	shell  informs
		       the user	of the arrival of mail in the specified	file.

       MAILCHECK       This  parameter	specifies  how	often (in seconds) the
		       shell will check	for the	arrival	of mail	in  the	 files
		       specified  by  the MAILPATH or MAIL parameters. The de-
		       fault value is 600 seconds (10 minutes).	If set	to  0,
		       the shell will check before each	prompt.

       MAILPATH	       A colon-separated list of file names. If	this parameter
		       is set, the shell informs the user of  the  arrival  of
		       mail  in	any of the specified files. Each file name can
		       be followed by %	and a message  that  will  be  printed
		       when the	modification time changes. The default message
		       is, you have mail.

       PS1	       Primary prompt string, by default " $ ".

       PS2	       Secondary prompt	string,	by default " > ".

       IFS	       Internal	field separators,  normally  space,  tab,  and
		       newline (see Blank Interpretation section).

       SHACCT	       If this parameter is set	to the name of a file writable
		       by the user, the	shell will write an accounting	record
		       in the file for each shell procedure executed.

       SHELL	       When  the  shell	 is  invoked, it scans the environment
		       (see Environment	section	below) for this	name.

       See environ(5) for descriptions of the following	environment  variables
       that affect the execution of sh:	LC_CTYPE and LC_MESSAGES.

       The  shell  gives default values	to PATH, PS1, PS2, MAILCHECK, and IFS.
       Default values for HOME and MAIL	are set	by login(1).

   Blank Interpretation
       After parameter and command substitution, the results  of  substitution
       are  scanned  for  internal  field separator characters (those found in
       IFS) and	split into distinct arguments where such characters are	found.
       Explicit	 null  arguments  ("" or '') are retained. Implicit null argu-
       ments (those resulting from parameters that have	 no  values)  are  re-

   Input/Output	Redirection
       A command's input and output may	be redirected using a special notation
       interpreted by the shell. The following may appear anywhere in  a  sim-
       ple-command or may precede or follow a command and are not passed on as
       arguments to the	invoked	command. Note: Parameter and command substitu-
       tion occurs before word or digit	is used.

       <word	       Use file	word as	standard input (file descriptor	0).

       >word	       Use  file  word as standard output (file	descriptor 1).
		       If the file does	not exist, it is  created;  otherwise,
		       it is truncated to zero length.

       >>word	       Use  file  word as standard output. If the file exists,
		       output is appended to it	by first seeking to  the  EOF.
		       Otherwise, the file is created.

       <>word	       Open  file word for reading and writing as standard in-

       <<[-]word       After parameter and command  substitution  is  done  on
		       word, the shell input is	read up	to the first line that
		       literally matches the resulting word, or	to an EOF. If,
		       however,	the hyphen (-) is appended to <<:

			   1.  leading	tabs are stripped from word before the
			       shell input is read (but	 after	parameter  and
			       command substitution is done on word);

			   2.  leading	tabs are stripped from the shell input
			       as it is	read and before	each line is  compared
			       with word; and

			   3.  shell  input  is	read up	to the first line that
			       literally matches the resulting word, or	to  an

		       If any character	of word	is quoted (see Quoting section
		       later), no additional processing	is done	to  the	 shell
		       input. If no characters of word are quoted:

			   1.  parameter and command substitution occurs;

			   2.  (escaped) \newlines are removed;	and

			   3.  \  must	be  used to quote the characters \, $,
			       and `.

		       The resulting document becomes the standard input.

       <&digit	       Use the file associated with file descriptor  digit  as
		       standard	input. Similarly for the standard output using

       <&-	       The standard input is closed. Similarly for  the	 stan-
		       dard output using >&-.

       If  any	of the above is	preceded by a digit, the file descriptor which
       will be associated with the file	is that	specified by  the  digit  (in-
       stead of	the default 0 or 1). For example:

       ... 2>&1

       associates  file	 descriptor  2 with the	file currently associated with
       file descriptor 1.

       The order in which redirections are specified is	significant. The shell
       evaluates redirections left-to-right. For example:

       ... 1>xxx 2>&1

       first  associates  file	descriptor 1 with file xxx. It associates file
       descriptor 2 with the file associated with file descriptor 1 (that  is,
       xxx).  If  the  order  of redirections were reversed, file descriptor 2
       would be	associated with	the terminal (assuming file descriptor	1  had
       been) and file descriptor 1 would be associated with file xxx.

       Using  the terminology introduced on the	first page, under Commands, if
       a command is composed of	several	simple commands, redirection  will  be
       evaluated for the entire	command	before it is evaluated for each	simple
       command.	That is, the shell evaluates redirection for the entire	 list,
       then each pipeline within the list, then	each command within each pipe-
       line, then each list within each	command.

       If a command is followed	by &, the default standard input for the  com-
       mand  is	 the empty file, /dev/null. Otherwise, the environment for the
       execution of a command contains the file	descriptors  of	 the  invoking
       shell as	modified by input/output specifications.

   File	Name Generation
       Before  a  command  is  executed,  each command word is scanned for the
       characters *, ?,	and [. If one of these characters appears the word  is
       regarded	 as a pattern. The word	is replaced with alphabetically	sorted
       file names that match the pattern.  If  no  file	 name  is  found  that
       matches the pattern, the	word is	left unchanged.	The character .	at the
       start of	a file name or immediately following a /, as well as the char-
       acter / itself, must be matched explicitly.

       *	       Matches any string, including the null string.

       ?	       Matches any single character.

       [...]	       Matches	any  one of the	enclosed characters. A pair of
		       characters separated by - matches any  character	 lexi-
		       cally between the pair, inclusive. If the first charac-
		       ter following the opening [ is a	!, any	character  not
		       enclosed	is matched.

       Notice  that  all quoted	characters (see	below) must be matched explic-
       itly in a filename.

       The following characters	have a special meaning to the shell and	 cause
       termination of a	word unless quoted:

       ;  &  (	)  |  ^	 <  >  newline	space  tab

       A  character  may be quoted (that is, made to stand for itself) by pre-
       ceding it with a	backslash (\) or inserting it between a	pair of	 quote
       marks  ('' or ""). During processing, the shell may quote certain char-
       acters to prevent them from taking on a	special	 meaning.  Backslashes
       used  to	 quote a single	character are removed from the word before the
       command is executed. The	pair \newline is removed from  a  word	before
       command and parameter substitution.

       All  characters enclosed	between	a pair of single quote marks (''), ex-
       cept a single quote, are	quoted by the shell. Backslash has no  special
       meaning	inside	a  pair	of single quotes. A single quote may be	quoted
       inside a	pair of	double quote marks (for	example, "'"),	but  a	single
       quote can not be	quoted inside a	pair of	single quotes.

       Inside a	pair of	double quote marks (""), parameter and command substi-
       tution occurs and the shell quotes the results to avoid blank interpre-
       tation  and  file  name	generation.  If	 $* is within a	pair of	double
       quotes, the positional parameters are substituted and quoted, separated
       by quoted spaces	("$1 $2	..."). However,	if $@ is within	a pair of dou-
       ble quotes, the positional parameters are substituted and quoted, sepa-
       rated  by  unquoted spaces ("$1""$2"  ... ). \ quotes the characters \,
       `, , (comma), and $. The	pair \newline is removed before	parameter  and
       command	substitution. If a backslash precedes characters other than \,
       `, , (comma), $,	and newline, then the backslash	itself	is  quoted  by
       the shell.

       When used interactively,	the shell prompts with the value of PS1	before
       reading a command. If at	any time a newline is typed and	further	 input
       is  needed  to  complete	 a command, the	secondary prompt (that is, the
       value of	PS2) is	issued.

       The environment (see environ(5))	is a list of name-value	pairs that  is
       passed  to  an  executed	 program  in the same way as a normal argument
       list. The shell interacts with the environment in several ways. On  in-
       vocation,  the  shell scans the environment and creates a parameter for
       each name found,	giving it the corresponding value.  If the user	 modi-
       fies  the  value	 of any	of these parameters or creates new parameters,
       none of these affects the environment unless the	export command is used
       to  bind	 the shell's parameter to the environment (see also set	-a). A
       parameter may be	removed	from the environment with the  unset  command.
       The  environment	 seen  by any executed command is thus composed	of any
       unmodified name-value pairs originally inherited	by  the	 shell,	 minus
       any pairs removed by unset, plus	any modifications or additions,	all of
       which must be noted in export commands.

       The environment for any simple-command may be augmented by prefixing it
       with one	or more	assignments to parameters. Thus:

       TERM=450	 command


       (export TERM; TERM=450;	 command

       are  equivalent as far as the execution of command is concerned if com-
       mand is not a Special Command. If command is a Special Command, then

       TERM=450	  command

       will modify the TERM variable in	the current shell.

       If the -k flag is set, all keyword arguments are	placed in the environ-
       ment,  even if they occur after the command name. The following example
       first prints a=b	c and c:

       echo a=b	 c

       a=b  c

       set  -k

       echo a=b	 c


       The INTERRUPT and QUIT signals for an invoked command  are  ignored  if
       the command is followed by &. Otherwise,	signals	have the values	inher-
       ited by the shell from its parent, with the exception of	signal 11 (but
       see also	the trap command below).

       Each  time  a  command is executed, the command substitution, parameter
       substitution, blank interpretation, input/output	redirection, and file-
       name  generation	 listed	 above	are  carried  out. If the command name
       matches the name	of a defined function, the function is executed	in the
       shell process (note how this differs from the execution of shell	script
       files, which require a sub-shell	for invocation). If the	 command  name
       does  not  match	the name of a defined function,	but matches one	of the
       Special Commands	listed below, it is executed in	the shell process.

       The positional parameters $1, $2, ... are set to	the arguments  of  the
       function. If the	command	name matches neither a Special Command nor the
       name of a defined function, a new process is created and	an attempt  is
       made to execute the command via exec(2).

       The shell parameter PATH	defines	the search path	for the	directory con-
       taining the command. Alternative	directory names	 are  separated	 by  a
       colon (:). The default path is /usr/bin.	The current directory is spec-
       ified by	a null path name, which	can appear immediately after the equal
       sign, between two colon delimiters anywhere in the path list, or	at the
       end of the path list. If	the command name contains a / the search  path
       is  not	used. Otherwise, each directory	in the path is searched	for an
       executable file.	If the file has	execute	permission but is not an a.out
       file, it	is assumed to be a file	containing shell commands. A sub-shell
       is spawned to read it. A	parenthesized command is also  executed	 in  a

       The location in the search path where a command was found is remembered
       by the shell (to	help avoid unnecessary execs later).  If  the  command
       was  found  in a	relative directory, its	location must be re-determined
       whenever	the current directory changes. The shell  forgets  all	remem-
       bered  locations	 whenever  the PATH variable is	changed	or the hash -r
       command is executed (see	below).

   Special Commands
       Input/output redirection	is now permitted for these commands. File  de-
       scriptor	1 is the default output	location. When Job Control is enabled,
       additional Special Commands are added to	the shell's  environment  (see
       Job Control section below).


	   No effect; the command does nothing.	A zero exit code is returned.

       . filename

	   Read	and execute commands from filename and return. The search path
	   specified by	PATH is	used to	find the  directory  containing	 file-

       bg [%jobid ...]

	   When	 Job Control is	enabled, the bg	command	is added to the	user's
	   environment to manipulate jobs. Resumes the execution of a  stopped
	   job	in the background. If %jobid is	omitted	the current job	is as-
	   sumed. (See Job Control section below for more detail.)

       break [ n ]

	   Exit	from the enclosing for or while	loop, if any. If n  is	speci-
	   fied, break n levels.

       cd [ argument ]

	   Change  the current directory to argument. The shell	parameter HOME
	   is the default argument. The	shell  parameter  CDPATH  defines  the
	   search  path	for the	directory containing argument. Alternative di-
	   rectory names are separated by a colon (:).	The  default  path  is
	   <null> (specifying the current directory). Note: The	current	direc-
	   tory	is specified by	a null path name, which	can appear immediately
	   after  the equal sign or between the	colon delimiters anywhere else
	   in the path list. If	argument begins	with a / the  search  path  is
	   not used. Otherwise,	each directory in the path is searched for ar-

       chdir [ dir ]

	   chdir changes the shell's working directory to directory dir. If no
	   argument is given, change to	the home directory of the user.	If dir
	   is a	relative pathname not found in the  current  directory,	 check
	   for	it  in those directories listed	in the CDPATH variable.	If dir
	   is the name of a shell variable whose value starts with a /,	change
	   to the directory named by that value.

       continue	[ n ]

	   Resume  the next iteration of the enclosing for or while loop. If n
	   is specified, resume	at the n-th enclosing loop.

       echo [ arguments	... ]

	   The words in	arguments are written to the shell's standard  output,
	   separated by	space characters. See echo(1) for fuller usage and de-

       eval [ argument ... ]

	   The arguments are read as input to the shell	and the	resulting com-
	   mand(s) executed.

       exec [ argument ... ]

	   The command specified by the	arguments is executed in place of this
	   shell without creating a new	process.  Input/output	arguments  may
	   appear  and,	 if  no	other arguments	are given, cause the shell in-
	   put/output to be modified.

       exit [ n	]

	   Causes the calling shell or shell script to exit with the exit sta-
	   tus	specified by n.	If n is	omitted	the exit status	is that	of the
	   last	command	executed (an EOF will also cause the shell to exit.)

       export [	name ... ]

	   The given names are marked for automatic export to the  environment
	   of subsequently executed commands. If no arguments are given, vari-
	   able	names that have	been marked  for  export  during  the  current
	   shell's  execution are listed. (Variable names exported from	a par-
	   ent shell are listed	only if	they have been exported	 again	during
	   the current shell's execution.) Function names are not exported.

       fg [%jobid ...]

	   When	 Job Control is	enabled, the fg	command	is added to the	user's
	   environment to manipulate jobs. This	command	resumes	the  execution
	   of  a  stopped  job	in  the	foreground and also moves an executing
	   background job into the foreground. If %jobid is omitted, the  cur-
	   rent	 job  is  assumed. (See	Job Control section below for more de-


	   Use in shell	scripts	to support command syntax standards  (see  in-
	   tro(1)).  This  command parses positional parameters	and checks for
	   legal options. See getoptcvt(1) for usage and description.

       hash [ -r ] [ name ... ]

	   For each name, the location in the search path of the command spec-
	   ified by name is determined and remembered by the shell. The	-r op-
	   tion	causes the shell to forget all remembered locations. If	no ar-
	   guments  are	 given,	 information about remembered commands is pre-
	   sented. Hits	is the number of times a command has been  invoked  by
	   the shell process. Cost is a	measure	of the work required to	locate
	   a command in	the search path. If a command is found in a "relative"
	   directory in	the search path, after changing	to that	directory, the
	   stored location of that command is recalculated. Commands for which
	   this	 will be done are indicated by an asterisk (*) adjacent	to the
	   hits	information. Cost will be incremented when  the	 recalculation
	   is done.

       jobs [-p|-l] [%jobid ...]
       jobs -x command [arguments]

	   Reports  all	 jobs that are stopped or executing in the background.
	   If %jobid is	omitted, all jobs that are stopped or running  in  the
	   background  will  be	 reported.  (See Job Control section below for
	   more	detail.)

       kill [ -sig ] %job ...
       kill -l

	   Sends either	the TERM (terminate) signal or the specified signal to
	   the specified jobs or processes. Signals are	either given by	number
	   or by names (as given in signal.h(3HEAD)  stripped  of  the	prefix
	   "SIG"  with the exception that SIGCHD is named CHLD). If the	signal
	   being sent is TERM (terminate) or HUP (hangup),  then  the  job  or
	   process will	be sent	a CONT (continue) signal if it is stopped. The
	   argument job	can be the process id of a process that	is not a  mem-
	   ber	of one of the active jobs. See Job Control section below for a
	   description of the format of	job. In	the second form, kill -l,  the
	   signal numbers and names are	listed.	(See kill(1)).

       login [ argument	... ]

	   Equivalent  to `exec	login argument....' See	login(1) for usage and

       newgrp [	argument ]

	   Equivalent to exec newgrp argument. See newgrp(1) for usage and de-


	   Print  the  current working directory. See pwd(1) for usage and de-

       read name ...

	   One line is read from the standard input and,  using	 the  internal
	   field  separator,  IFS  (normally  space  or	 tab), to delimit word
	   boundaries, the first word is assigned to the first name, the  sec-
	   ond	word to	the second name, and so	forth, with leftover words as-
	   signed to the last name. Lines can  be  continued  using  \newline.
	   Characters  other than newline can be quoted	by preceding them with
	   a backslash.	These backslashes are removed  before  words  are  as-
	   signed  to  names,  and  no interpretation is done on the character
	   that	follows	the backslash. The return code is 0, unless an EOF  is

       readonly	[ name ... ]

	   The	given  names  are  marked readonly and the values of the these
	   names may not be changed by subsequent assignment. If no  arguments
	   are given, a	list of	all readonly names is printed.

       return [	n ]

	   Causes  a function to exit with the return value specified by n. If
	   n is	omitted, the return status is that of the  last	 command  exe-

       set [ -aefhkntuvx [ argument ...	] ]

	   -a	    Mark variables which are modified or created for export.

	   -e	    Exit  immediately  if a command exits with a non-zero exit

	   -f	    Disable file name generation.

	   -h	    Locate and remember	function commands as functions are de-
		    fined  (function  commands	are  normally located when the
		    function is	executed).

	   -k	    All	keyword	arguments are placed in	the environment	for  a
		    command, not just those that precede the command name.

	   -n	    Read commands but do not execute them.

	   -t	    Exit after reading and executing one command.

	   -u	    Treat unset	variables as an	error when substituting.

	   -v	    Print shell	input lines as they are	read.

	   -x	    Print commands and their arguments as they are executed.

	   -	    Do not change any of the flags; useful in setting $1 to -.

	   Using  +  rather  than - causes these flags to be turned off. These
	   flags can also be used upon invocation of the  shell.  The  current
	   set	of flags may be	found in $-. The remaining arguments are posi-
	   tional parameters and are assigned, in order, to $1,	$2, ...	If  no
	   arguments are given,	the values of all names	are printed.

       shift [ n ]

	   The	positional  parameters from $n+1 ... are renamed $1 ...	. If n
	   is not given, it is assumed to be 1.

       stop pid	...

	   Halt	execution of the process number	pid. (see ps(1)).


	   Stops the execution of the current shell (but not if	it is the  lo-
	   gin shell).


	   Evaluate  conditional  expressions.	See  test(1) for usage and de-


	   Print the accumulated user and system times for processes run  from
	   the shell.

       trap [ argument n [ n2 ... ]]

	   The	command	argument is to be read and executed when the shell re-
	   ceives numeric  or  symbolic	 signal(s)  (n).  (Note:  argument  is
	   scanned once	when the trap is set and once when the trap is taken.)
	   Trap	commands are executed in order of signal number	or correspond-
	   ing	symbolic names.	Any attempt to set a trap on a signal that was
	   ignored on entry to the current shell is ineffective. An attempt to
	   trap	 on signal 11 (memory fault) produces an error.	If argument is
	   absent, all trap(s) n are reset to their original values. If	 argu-
	   ment	is the null string, this signal	is ignored by the shell	and by
	   the commands	it invokes. If n is 0, the command  argument  is  exe-
	   cuted  on  exit  from the shell. The	trap command with no arguments
	   prints a list of commands associated	with each signal number.

       type [ name ... ]

	   For each name, indicate how it would	be interpreted if  used	 as  a
	   command name.

       ulimit [	[-HS] [-a | -cdfnstv] ]
       ulimit [	[-HS] [-c | -d | -f | -n | -s |	-t | -v] ] limit

	   ulimit  prints  or  sets hard or soft resource limits. These	limits
	   are described in getrlimit(2).

	   If limit is not present, ulimit prints the  specified  limits.  Any
	   number  of  limits may be printed at	one time. The -a option	prints
	   all limits.

	   If limit is present,	ulimit sets the	specified limit	to limit.  The
	   string  unlimited  requests	the largest valid limit. Limits	may be
	   set for only	one resource at	a time.	Any user may set a soft	 limit
	   to any value	below the hard limit. Any user may lower a hard	limit.
	   Only	a super-user may raise a hard limit. (See su(1M).)

	   The -H option specifies a hard limit. The  -S  option  specifies  a
	   soft	 limit.	 If  neither option is specified, ulimit will set both
	   limits and print the	soft limit.

	   The following options specify the resource whose limits are	to  be
	   printed  or	set. If	no option is specified,	the file size limit is
	   printed or set.

	   -c	    maximum core file size (in 512-byte	blocks)

	   -d	    maximum size of data segment or heap (in kbytes)

	   -f	    maximum file size (in 512-byte blocks)

	   -n	    maximum file descriptor plus 1

	   -s	    maximum size of stack segment (in kbytes)

	   -t	    maximum CPU	time (in seconds)

	   -v	    maximum size of virtual memory (in kbytes)

	   Run the sysdef(1M) command to obtain	the  maximum  possible	limits
	   for	your  system.  The values reported are in hexadecimal, but can
	   be translated into decimal numbers using the	 bc(1)	utility.   See

	   As an example of ulimit, to limit the size of a core	file dump to 0
	   Megabytes, type the following:

	   ulimit -c 0

       umask [ nnn ]

	   The user file-creation mask is set to nnn (see umask(1)). If	nnn is
	   omitted, the	current	value of the mask is printed.

       unset [ name ...	]

	   For each name, remove the corresponding variable or function	value.
	   The variables PATH, PS1, PS2, MAILCHECK, and	IFS cannot be unset.

       wait [ n	]

	   Wait	for your background process whose process id is	n  and	report
	   its termination status. If n	is omitted, all	your shell's currently
	   active background processes are waited for and the return code will
	   be zero.

       If  the shell is	invoked	through	exec(2)	and the	first character	of ar-
       gument zero is -, commands are initially	 read  from  /etc/profile  and
       from $HOME/.profile, if such files exist. Thereafter, commands are read
       as described below, which is also the case when the shell is invoked as
       /usr/bin/sh. The	flags below are	interpreted by the shell on invocation
       only. Note: Unless the -c or -s flag is specified, the  first  argument
       is  assumed  to	be the name of a file containing commands, and the re-
       maining arguments are passed as positional parameters to	 that  command

       -c string       If  the	-c  flag  is  present  commands	 are read from

       -i	       If the -i flag is present or if	the  shell  input  and
		       output are attached to a	terminal, this shell is	inter-
		       active. In this case, TERMINATE	is  ignored  (so  that
		       kill  0	does not kill an interactive shell) and	INTER-
		       RUPT is caught and ignored (so that wait	is  interrupt-
		       ible). In all cases, QUIT is ignored by the shell.

       -p	       If  the	-p flag	is present, the	shell will not set the
		       effective user and group	IDs to the real	user and group

       -r	       If  the	-r  flag  is present the shell is a restricted
		       shell (see rsh(1M)).

       -s	       If the -s flag is present or if	no  arguments  remain,
		       commands	 are read from the standard input. Any remain-
		       ing arguments specify the positional parameters.	 Shell
		       output (except for Special Commands) is written to file
		       descriptor 2.

       The remaining flags and arguments are described under the  set  command

   Job Control (jsh)
       When the	shell is invoked as jsh, Job Control is	enabled	in addition to
       all of the functionality	described previously for  sh.  Typically,  Job
       Control	is  enabled  for  the  interactive shell only. Non-interactive
       shells typically	do not benefit from the	 added	functionality  of  Job

       With  Job Control enabled, every	command	or pipeline the	user enters at
       the terminal is called a	job. All jobs exist in one  of	the  following
       states:	foreground, background,	or stopped. These terms	are defined as

       1.  A job in the	foreground has read and	write access to	 the  control-
	   ling	terminal.

       2.  A  job  in the background is	denied read access and has conditional
	   write access	to the controlling terminal (see stty(1)).

       3.  A stopped job is a job that has been	placed in a  suspended	state,
	   usually as a	result of a SIGTSTP signal (see	signal.h(3HEAD)).

       Every  job that the shell starts	is assigned a positive integer,	called
       a job number which is tracked by	the shell and will be used as an iden-
       tifier  to indicate a specific job. Additionally, the shell keeps track
       of the current and previous jobs. The current job is  the  most	recent
       job  to be started or restarted.	The previous job is the	first non-cur-
       rent job.

       The acceptable syntax for a Job Identifier is of	the form:


       where jobid may be specified in any of the following formats:

       % or +	       For the current job.

       -	       For the previous	job.

       ?_string_       Specify the job for which  the  command	line  uniquely
		       contains	string.

       n	       For job number n.

       pref	       Where  pref is a	unique prefix of the command name. For
		       example,	if the command ls -l name were running in  the
		       background, it could be referred	to as %ls. pref	cannot
		       contain blanks unless it	is quoted.

       When Job	Control	is enabled, the	following commands are	added  to  the
       user's environment to manipulate	jobs:

       bg [%jobid ...]

	   Resumes the execution of a stopped job in the background. If	%jobid
	   is omitted the current job is assumed.

       fg [%jobid ...]

	   Resumes the execution of a stopped  job  in	the  foreground,  also
	   moves an executing background job into the foreground. If %jobid is
	   omitted the current job is assumed.

       jobs [-p|-l] [%jobid ...]
       jobs -x command [arguments]

	   Reports all jobs that are stopped or	executing in  the  background.
	   If  %jobid  is omitted, all jobs that are stopped or	running	in the
	   background will be reported.	 The following options will modify/en-
	   hance the output of jobs:

	   -l	    Report  the	 process group ID and working directory	of the

	   -p	    Report only	the process group ID of	the jobs.

	   -x	    Replace any	jobid found in command or arguments  with  the
		    corresponding  process  group ID, and then execute command
		    passing it arguments.

       kill [ -signal ]	%jobid

	   Builtin version of kill to provide the functionality	 of  the  kill
	   command for processes identified with a jobid.

       stop %jobid ...

	   Stops the execution of a background job(s).


	   Stops  the execution	of the current shell (but not if it is the lo-
	   gin shell).

       wait [%jobid ...]

	   wait	builtin	accepts	a job identifier. If %jobid  is	 omitted  wait
	   behaves as described	above under Special Commands.

   Large File Behavior
       See largefile(5)	for the	description of the behavior of sh and jsh when
       encountering files greater than or equal	to 2 Gbyte ( 2**31 bytes).

       Errors detected by the shell, such as syntax errors, cause the shell to
       return  a non-zero exit status. If the shell is being used non-interac-
       tively execution	of the shell file is abandoned.	Otherwise,  the	 shell
       returns the exit	status of the last command executed (see also the exit
       command above).

   jsh Only
       If the shell is invoked as jsh and an attempt is	made to	exit the shell
       while there are stopped jobs, the shell issues one warning:

       There are stopped jobs.

       This  is	 the  only message. If another exit attempt is made, and there
       are still stopped jobs they will	be sent	a SIGHUP signal	from the  ker-
       nel and the shell is exited.





       See attributes(5) for descriptions of the following attributes:

   /usr/bin/sh,	/usr/bin/jsh
       |      ATTRIBUTE	TYPE	     |	    ATTRIBUTE VALUE	   |
       |Availability		     |SUNWcsu			   |
       |CSI			     |Enabled			   |

       |      ATTRIBUTE	TYPE	     |	    ATTRIBUTE VALUE	   |
       |Availability		     |SUNWxcu4			   |
       |CSI			     |Enabled			   |

       intro(1), bc(1),	echo(1), getoptcvt(1), kill(1),	ksh(1),	login(1), new-
       grp(1), pfsh(1),	pfexec(1), ps(1), pwd(1),  set(1),  shell_builtins(1),
       stty(1),	 test(1),  umask(1),  wait(1), rsh(1M),	su(1M),	swap(1M), sys-
       def(1M),	dup(2),	exec(2), fork(2),  getrlimit(2),  pipe(2),  ulimit(2),
       setlocale(3C),  signal.h(3HEAD),	 passwd(4), profile(4),	attributes(5),
       environ(5), largefile(5), XPG4(5)

       The use of setuid shell scripts is strongly discouraged.

       Words used for filenames	in input/output	 redirection  are  not	inter-
       preted  for  filename  generation  (see	File  Name  Generation section
       above). For example, cat	file1 >a* will create a	file named a*.

       Because commands	in pipelines are run as	separate processes,  variables
       set in a	pipeline have no effect	on the parent shell.

       If  the input or	the output of a	while or until loop is redirected, the
       commands	in the loop are	run in	a  sub-shell,  and  variables  set  or
       changed there have no effect on the parent process:

	  while	read line

	  done < /etc/passwd
	  echo "lastline=$lastline"	  # lastline is	empty!

       In these	cases, the input or output can be redirected by	using exec, as
       in the following	example:

	  # Save standard input	(file descriptor 0) as file
	  # descriptor 3, and redirect standard	input from the file

	  exec 3<&0		  # save standard input	as fd 3
	  exec </etc/passwd	  # redirect input from	file

	  while	read line

	  exec 0<&3		  # restore standard input
	  exec 3<&-		  # close file descriptor 3
	  echo "$lastline"	  # lastline

       If you get the error message, "cannot fork, too	many  processes",  try
       using  the  wait(1)  command  to	clean up your background processes. If
       this doesn't help, the system process table is  probably	 full  or  you
       have too	many active foreground processes. There	is a limit to the num-
       ber of process ids associated with your login, and to  the  number  the
       system can keep track of.

       Only the	last process in	a pipeline can be waited for.

       If a command is executed, and a command with the	same name is installed
       in a directory in the search path before	the directory where the	origi-
       nal  command  was  found,  the shell will continue to exec the original
       command.	Use the	hash command to	correct	this situation.

       The Bourne shell	has a limitation on the	effective UID for  a  process.
       If  this	 UID  is  less	than 100 (and not equal	to the real UID	of the
       process), then the UID is reset to the real UID of the process.

       Because the shell implements both foreground and	background jobs	in the
       same  process  group, they all receive the same signals,	which can lead
       to unexpected behavior. It is, therefore, recommended  that  other  job
       control shells be used, especially in an	interactive environment.

       When  the shell executes	a shell	script that attempts to	execute	a non-
       existent	command	interpreter, the shell returns an erroneous diagnostic
       message that the	shell script file does not exist.

SunOS 5.10			  19 Sep 2003				 sh(1)


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