tclsh



tclsh(1)                       Tcl Applications                       tclsh(1)



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NAME

       tclsh - Simple shell containing Tcl interpreter


SYNOPSIS

       tclsh ?fileName arg arg ...?
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DESCRIPTION

       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, tclsh evaluates the file as a Tcl script just before reading  the
       first command from standard input.



SCRIPT FILES

       If  tclsh is invoked with arguments then the first argument is the name
       of a script file and 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  charac- │
       ter, ’\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 character 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
              #!/usr/local/bin/tclsh
       then you can invoke the script file directly from  your  shell  if  you
       mark  the  file  as  executable.   This  assumes  that  tclsh  has been
       installed in the default location in /usr/local/bin;  if it’s installed
       somewhere  else  then  you’ll  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:
              #!/bin/sh
              # the next line restarts using tclsh \
              exec tclsh "$0" "$@"
       This  approach  has  three advantages over the approach in the previous
       paragraph.  First, the location of the tclsh binary doesn’t 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
       itself 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 practise to install tclsh with │
       its version number as part of the name.   This  has  the  advantage  of │
       allowing  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.



VARIABLES

       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
                      arguments.

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

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



PROMPTS

       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  isn’t  yet complete; if tcl_prompt2 isn’t set then no
       prompt is output for incomplete commands.



STANDARD CHANNELS

       See Tcl_StandardChannels for more explanations.



SEE ALSO

       fconfigure(n), tclvars(n)



KEYWORDS

       argument, interpreter, prompt, script file, shell



Tcl                                                                   tclsh(1)

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