This is an application created by default by the core distribution.
It is a simple shell interpreter, and is frequently used by
developers writing tcl scripts.

A user of tclsh (or of [wish], the interactive tcl shell with Tk automatically
loaded), should be aware that there are a few differences between typing
tcl statements to the shell in interactive mode and typing tcl commands
into a file and then executing it.

   * [tcl_interactive]
   interactive:   this variable is set 
   command file:   this variable is set to 0

   * unknown proc differences - if tclsh is unable to recognize the command typed, the unknown proc is invoked.
   interactive:   unknown will automatically pass command to exec .
   command file:   the coder must specify exec before any non-tcl commands

   * abbreviations 
   interactive:   the unknown command looks to see if the typed command is an abbreviation of an existing command and, if it is, invokes it.  Thus in interactive mode it's possible to write
    set fp [op $myfile]
   command file:   would require [open] be written out in full.

   * standard output displayed 
   interactive:   stdout appears to the screen when you type commands
   command file:   the coder must specify puts to get the output from a command to display to the screen

   * byte-compilation
   interactive:   prompt commands are byte compiled
   command file:   top level commands are not byte compiled

----
[Category Application], a part of the [Tcl] package.