KILL(2-POSIX)       RISC/os Reference Manual        KILL(2-POSIX)



NAME
     kill - send a signal to a process or a group of processes

SYNOPSIS
     #include <sys/types.h>
     #include <signal.h>

     int kill (pid, sig)
     pidt pid;
     int sig;

DESCRIPTION
     kill sends a signal to a process or a group of processes.
     The process or group of processes to which the signal is to
     be sent is specified by pid.  The signal that is to be sent
     is specified by sig and is either one from the list given in
     <signal.h> 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.

     For a process to have permission to send a signal to the
     process designated by pid, the real or saved set-user-ID of
     the sending process must match the real or effective user ID
     of the receiving process, unless the process is the
     superuser.

     The processes with a process ID of 0 and a process ID of 1
     are special processes [see intro(2)] and will be referred to
     below as proc0 and proc1, respectively.

     If pid is greater than zero, sig will be sent to the process
     whose process ID is equal to pid.  pid may equal 1.

     If pid is 0, sig will be sent to all processes excluding
     proc0 and proc1 whose process group ID is equal to the pro-
     cess group ID of the sender, and for which the process has
     permission to send a signal.

     If pid is -1 and the effective user ID of the sender is not
     super-user, sig will be sent to all processes excluding
     proc0 and proc1 whose real user ID is equal to the effective
     user ID of the sender.

     If pid is -1 and the effective user ID of the sender is
     super-user, sig will be sent to all processes excluding
     proc0 and proc1.

     If pid is negative but not -1, sig will be sent to all
     processes whose process group ID is equal to the absolute
     value of pid, and for which the process has permission to
     send a signal.




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KILL(2-POSIX)       RISC/os Reference Manual        KILL(2-POSIX)



     If the value of pid causes sig to be generated for the send-
     ing process, and if sig is not blocked, either sig or at
     least one pending unblocked signal is delivered to the send-
     ing process before kill returns.

     If sig is SIGCONT, the user ID checks are not applied when
     SIGCONT is being sent to a process that is a member of the
     same session as the sending process.

ERRORS
     kill will fail and no signal will be sent if one or more of
     the following are true:

     [EINVAL]            sig is not a valid signal number.

     [EINVAL]            sig is SIGKILL and pid is 1 (proc1).

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

     [EPERM]             The process does not have permission to
                         send the signal to any process.

SEE ALSO
     getpid(2), setsid(2), signal(2), sigaction(2).

DIAGNOSTICS
     Upon successful completion, a value of 0 is returned.  Oth-
     erwise, a value of -1 is returned and errno is set to indi-
     cate the error.

























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