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  provided  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