NAME

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

SYNOPSIS

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

       void
       kern_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 kern_psignal() function posts signal  number  signum  to  the  process  represented  by  the  process
       structure  p.   The  kern_psignal()  function  used  to  be  called psignal() but was renamed in order to
       eliminate a name collision with the libc function of that name and facilitate code  reuse.   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 kern_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 kern_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 kern_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)

HISTORY

       The psignal() function was renamed to kern_psignal() in FreeBSD 9.0.

Debian                                           October 8, 2011                                      PSIGNAL(9)