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PSIGNAL(9)	       FreeBSD Kernel Developer's Manual	    PSIGNAL(9)

     psignal, pgsignal,	gsignal	-- post	signal to a process or process group

     psignal(struct proc *p, int signum);

     pgsignal(struct pgrp *pgrp, int signum, int checkctty);

     gsignal(int pgid, int signum);

     These functions post a signal to one or more processes. The argument
     signum common to all three	functions should be in the range [1-NSIG].

     The psignal() function posts signal number	signum to the process repre-
     sented by the process structure p.	 With a	few exceptions noted below,
     the target	process	signal disposition is updated and is marked as
     runnable, so further handling of the signal is done in the	context	of the
     target process after a context switch. Note that psignal()	does not by
     itself cause a context switch to happen.

     The target	process	is not marked as runnable in the following cases:

	   +o   The target process is sleeping uninterruptibly. The signal will
	       be noticed when the process returns from	the system call	or

	   +o   The target process is currently ignoring	the signal.

	   +o   If a stop signal	is sent	to a sleeping process that takes the
	       default action (see sigaction(2)), the process is stopped with-
	       out awakening it.

	   +o   SIGCONT restarts	a stopped process (or puts them	back to	sleep)
	       regardless of the signal	action (e.g., blocked or ignored).

     If	the target process is being traced psignal() behaves as	if the target
     process were taking the default action for	signum.	 This allows the trac-
     ing process to be notified	of the signal.

     The pgsignal() function posts signal number signum	to each	member of the
     process group described by	pgrp.  If checkctty is non-zero, the signal
     will be posted only to processes that have	a controlling terminal.
     pgsignal()	is implemented by walking along	the process list headed	by the
     field pg_members of the process group structure pointed at	by pgrp	and
     calling psignal() as appropriate. If pgrp is NULL no action is taken.

     The gsignal() function posts signal number	signum to each member of the
     process group identified by the group id pgid.  gsignal() first finds the
     group structure associated	with pgid, then	invokes	pgsignal() with	the
     argument checkctty	set to zero. If	pgid is	zero no	action is taken.

     sigaction(2), tsleep(9)

FreeBSD	2.2.1			 June 22, 1996			 FreeBSD 2.2.1


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