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tclsh(1) Tcl Applications tclsh(1) 





NAME


tclsh - Simple shell containing Tcl interpreter






SYNOPSIS


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










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 standard
    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.








SCRIPT FILES


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 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 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 characters 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
    following three lines:




#!/bin/sh
# 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 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 practice 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:



  

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

  

  
Contains a Tcl list whose elements are the arg arguments, in order,
      or an empty string if there are no arg arguments.

  

  
Contains fileName if it was specified. Otherwise, contains the name
      by which tclsh was invoked.

  

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

  








PROMPTS


When tclsh is invoked interactively it normally prompts for
    each command 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.








STANDARD CHANNELS


See Tcl_StandardChannels for more explanations.








SEE ALSO


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








KEYWORDS


argument, interpreter, prompt, script file, shell







  

    
    Tcl