FreeBSD 4.11 manual page repository

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



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


      #include <sys/types.h>
      #include <sys/signalvar.h>
      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:
                  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 with‐
                out 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 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)


Based on BSD UNIX
FreeBSD is an advanced operating system for x86 compatible (including Pentium and Athlon), amd64 compatible (including Opteron, Athlon64, and EM64T), UltraSPARC, IA-64, PC-98 and ARM architectures. It is derived from BSD, the version of UNIX developed at the University of California, Berkeley. It is developed and maintained by a large team of individuals. Additional platforms are in various stages of development.