signal(3)



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_AsyncCre-
       ate().  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  inter-
       preter  which added the signal handler otherwise. At least until a bet-
       ter 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 UNHAN-
       DLED 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)

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