debian man page for signal

signal(3tcl)															      signal(3tcl)

NAME
       signal - dynamically loadable signal handling for Tcl/Tk

SYNOPSIS
       signal (add|delete|print|version) [options]

COMMANDS
   add signo proc [-async]
       Adds  a signal handler for signal signo through proc proc.  Signals can be provided by number, or the most common ones are provided by name
       (e.g., SIGHUP).	The proc is any Tcl procedure, and it is evaluated when the signal comes in.  It will be provided no arguments.

       Signal handlers have Posix semantics - they persist until reset.

       If -async is used, the signal handler is created using Tcl_AsyncCreate().  Checks for the signal are very frequent (each evaluation)  using
       this  technique,  but one doesn't know quite where evaluation is or how to handle errors in this situation. The code will evaluate the pro-
       vided procedure in the current interpreter if available, and in the interpreter which added the signal handler otherwise. At least until  a
       better scheme is suggested.

       The  -async  is	especially  useful  to interrupt "runaway" procs, or to cause a quick exit; the default mechanism simply waits for another
       MainLoop cycle.

   signal delete signo
       Restores handling of signal signo to the default ( SIG_DFL ).

   signal print
       Prints the handling of all signals with handlers. Formatted as
	signal ----> procedure or as
	signal !---> procedure

       if the signal is handled asynchronously

   signal print signo
       Prints the procedure for handling signal signo.	Prints the word UNHANDLED if no signal handler is active for that signal.

   signal version
       Returns the string representing the current version of the package

AUTHOR
       Michael Schwartz <mschwart@nyx.net>. Tilman Kranz <tilde@tk-sls.de> patched this for wider portability on Linux

Tcl Signal Extension						    1.4.0.1 Tcl 						      signal(3tcl)