kill(2)                                                             kill(2)




 NAME    [Toc]    [Back]
      kill(), raise() - send a signal to a process or a group of processes

 SYNOPSIS    [Toc]    [Back]
      #include <signal.h>

      int kill(pid_t pid, int sig);

      int raise(int sig);

 DESCRIPTION    [Toc]    [Back]
      The kill() system call sends a signal to a process or a group of
      processes, as specified by pid.  The signal to be sent is specified by
      sig and is either one from the list given in signal(2), or 0.

      The raise() system call sends a signal to the executing program.  The
      signal to be sent is specified by sig and is either one from the list
      given in signal(2), or 0.

      If sig is 0 (the null signal), error checking is performed but no
      signal is actually sent.  This can be used to check the validity of
      pid.

      The real or effective user ID of the sending process must match the
      real or saved user ID of the receiving process unless the effective
      user ID of the sending process is a user who has appropriate
      privileges.

      As a single special case, the continue signal SIGCONT can be sent to
      any process that is a member of the same session as the sending
      process.

      The value KILL_ALL_OTHERS is defined in the file <sys/signal.h> and is
      guaranteed not to be the ID of any process in the system or the
      negation of the ID of any process in the system.

      If pid is greater than zero and not equal to KILL_ALL_OTHERS, sig is
      sent to the process whose process ID is equal to pid.  pid can equal 1
      unless sig is SIGKILL or SIGSTOP.

      If pid is 0, sig is sent to all processes excluding special system
      processes whose process group ID is equal to the process group ID of
      the sender.

      If pid is -1 and the effective user ID of the sender is not a user who
      has appropriate privileges.  sig is sent to all processes excluding
      special system processes whose real or saved user ID is equal to the
      real or effective user ID of the sender.

      If pid is -1 and the effective user ID of the sender is a user who has
      appropriate privileges, sig is sent to all processes excluding special



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 kill(2)                                                             kill(2)




      system processes.

      If pid is KILL_ALL_OTHERS, kill() behaves much as when pid is equal to
      -1, except that sig is not sent to the calling process.

      If pid is negative but not -1 or KILL_ALL_OTHERS, sig is sent to all
      processes (excluding special system processes) whose process group ID
      is equal to the absolute value of pid, and whose real and/or effective
      user ID meets the constraints described above for matching user IDs.

 RETURN VALUE    [Toc]    [Back]
      Upon successful completion, a value of 0 is returned.  Otherwise, a
      value of -1 is returned and errno is set to indicate the error.

 ERRORS    [Toc]    [Back]
      If kill() fails, no signal is sent.  errno is set to one of the
      following values.

           [EINVAL]       sig is neither a valid signal number nor zero.

           [EINVAL]       sig is SIGKILL or SIGSTOP and pid is 1 (process
                          1).

           [EPERM]        The user ID of the sending process is not a user
                          who has appropriate privileges and its real or
                          effective user ID does not match the real or saved
                          user ID of the receiving process.

           [EPERM]        The sending and receiving processes are not in the
                          same session and the real or effective user ID
                          does not match the real or saved user ID of the
                          receiving process.

           [ESRCH]        No process or process group can be found
                          corresponding to that specified by pid.

      If raise() fails, no signal is sent.  errno is set to one of the
      following values.

           [EINVAL]       sig is neither a valid signal number nor zero.

 APPLICATION USAGE    [Toc]    [Back]
    Threads Considerations
      kill() can be used to post signals to another process but cannot be
      used to post signals to a specific thread in another process.  For
      information on posting signals to specific threads within the same
      process, see pthread_kill(3T).

    LWP (Lightweight Processes) Considerations    [Toc]    [Back]
      Signals cannot be posted to specific LWPs in another process.




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 kill(2)                                                             kill(2)




 AUTHOR    [Toc]    [Back]
      kill() was developed by HP, AT&T, and the University of California,
      Berkeley.

 SEE ALSO    [Toc]    [Back]
      kill(1), getpid(2), setsid(2), signal(2), sigqueue(2),
      pthread_kill(3T).

 STANDARDS CONFORMANCE    [Toc]    [Back]
      kill(): AES, SVID2, SVID3, XPG2, XPG3, XPG4, FIPS 151-2, POSIX.1

      raise(): AES, SVID3, XPG4, ANSI C


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