NAME

       psignal, pgsignal, gsignal, tdsignal — post signal to a thread, process, or process group

SYNOPSIS

       #include <sys/types.h>
       #include <sys/signalvar.h>

       void
       psignal(struct proc *p, int signum);

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

       void
       gsignal(int pgid, int signum);

       void
       tdsignal(struct thread *td, int signum);

DESCRIPTION

       These  functions  post  a signal to a thread or 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 represented 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:

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

             •   The target process is currently ignoring the signal.

             •   If a  stop  signal  is  sent  to  a  sleeping  process  that  takes  the  default  action  (see
                 sigaction(2)), the process is stopped without awakening it.

             •   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 tracing 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.

       The tdsignal() function posts signal number signum to the thread represented by the thread structure td.

SEE ALSO

       sigaction(2), signal(9), tsleep(9)

Debian                                           October 8, 2011                                      PSIGNAL(9)