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, 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 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 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.
If you create a Tcl script in a file whose first line is
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 "$0" "$@"
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.
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.|
Contains 1 if tclsh is running interactively (no
fileName was specified and standard input is a terminal-like
device), 0 otherwise.
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 isnt yet complete; if tcl_prompt2 isnt set then no prompt is output for incomplete commands.
See Tcl_StandardChannels for more explanations.