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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 "$0" "$@"




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:


  
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
      arguments, in order, or an empty string if there are no arg
      arguments.





  
argv0

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





  
tcl_interactive

  
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(3tcl), fconfigure(3tcl), tclvars(3tcl)

 


KEYWORDS

argument, interpreter, prompt, script file, shell



  

    
    Tcl