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tclsh(1)		       Tcl Applications			      tclsh(1)


       tclsh - Simple shell containing Tcl interpreter

       tclsh ?-encoding	name? ?fileName	arg arg	...?

       Tclsh  is  a  shell-like	 application  that reads Tcl commands from its
       standard	input or from a	file and evaluates them.  If invoked  with  no
       arguments  then	it runs	interactively, reading Tcl commands from stan-
       dard input and printing command results and error messages to  standard
       output.	 It runs until the exit	command	is invoked or until it reaches
       end-of-file on its standard input.  If there exists a file .tclshrc (or
       tclshrc.tcl  on	the  Windows  platforms)  in the home directory	of the
       user, interactive tclsh evaluates the file as a Tcl script just	before
       reading the first command from standard input.

       If tclsh	is invoked with	arguments then the first few arguments specify |
       the name	of a script file, and, optionally, the encoding	 of  the  text |
       data  stored  in	 that  script file.  Any additional arguments are made
       available to the	script as variables (see below).  Instead  of  reading
       commands	 from  standard	 input	tclsh  will read Tcl commands from the
       named file;  tclsh will exit when it reaches the	end of the file.   The
       end of the file may be marked either by the physical end	of the medium,
       or by the character, "\032" ("\u001a", control-Z).  If  this  character
       is  present in the file,	the tclsh application will read	text up	to but
       not including the character.  An	application that requires this charac-
       ter in the file may safely encode it as "\032", "\x1a", or "\u001a"; or
       may generate it by use of commands such as format or binary.  There  is
       no  automatic  evaluation of .tclshrc when the name of a	script file is
       presented on the	tclsh command line, but	the  script  file  can	always
       source it if desired.

       If you create a Tcl script in a file whose first	line is
       then  you  can  invoke  the script file directly	from your shell	if you
       mark the	file as	executable.  This assumes  that	 tclsh	has  been  in-
       stalled	in the default location	in /usr/local/bin;  if it is installed
       somewhere else then you will have to modify the above  line  to	match.
       Many  UNIX  systems do not allow	the #! line to exceed about 30 charac-
       ters in length, so be sure that the tclsh executable  can  be  accessed
       with a short file name.

       An  even	better approach	is to start your script	files with the follow-
       ing three lines:
	      #	the next line restarts using tclsh \
	      exec tclsh "$0" ${1+"$@"}
       This approach has three advantages over the approach  in	 the  previous
       paragraph.  First, the location of the tclsh binary does	not have to be
       hard-wired into the script:  it can be anywhere in  your	 shell	search
       path.   Second,	it gets	around the 30-character	file name limit	in the
       previous	approach.  Third, this approach	will work even if tclsh	is it-
       self  a	shell  script (this is done on some systems in order to	handle
       multiple	architectures or operating systems:  the tclsh script  selects
       one  of	several	 binaries  to run).  The three lines cause both	sh and
       tclsh to	process	the script, but	the exec is only executed by  sh.   sh
       processes the script first;  it treats the second line as a comment and
       executes	the third line.	 The exec statement cause the  shell  to  stop
       processing  and	instead	 to  start  up	tclsh  to reprocess the	entire
       script.	When tclsh starts up, it treats	all three lines	 as  comments,
       since the backslash at the end of the second line causes	the third line
       to be treated as	part of	the comment on the second line.

       You should note that it is also common practice to install  tclsh  with
       its  version number as part of the name.	 This has the advantage	of al-
       lowing multiple versions	of Tcl to exist	on the same  system  at	 once,
       but  also  the  disadvantage  of	making it harder to write scripts that
       start up	uniformly across different versions of Tcl.

       Tclsh sets the following	Tcl variables:

       argc	      Contains a count of the number of	arg  arguments	(0  if
		      none), not including the name of the script file.

       argv	      Contains	a  Tcl	list  whose elements are the arg argu-
		      ments, in	order, or an empty string if there are no  arg

       argv0	      Contains	fileName if it was specified.  Otherwise, con-
		      tains the	name by	which tclsh was	invoked.

		      Contains 1 if tclsh is running interactively  (no	 file-
		      Name was specified and standard input is a terminal-like
		      device), 0 otherwise.

       When tclsh is invoked interactively it normally prompts for  each  com-
       mand  with  "%  ".   You	can change the prompt by setting the variables
       tcl_prompt1 and tcl_prompt2.  If	variable tcl_prompt1  exists  then  it
       must consist of a Tcl script to output a	prompt;	 instead of outputting
       a prompt	tclsh will evaluate the	script in tcl_prompt1.	 The  variable
       tcl_prompt2  is	used  in a similar way when a newline is typed but the
       current command is not yet complete; if tcl_prompt2 is not set then  no
       prompt is output	for incomplete commands.

       See Tcl_StandardChannels	for more explanations.

       encoding(n), fconfigure(n), tclvars(n)

       argument, interpreter, prompt, script file, shell

Tcl								      tclsh(1)


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