KILL(2)

NAME
kill - send signal to a process

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

int kill(pid_t pid, int sig);

DESCRIPTION
The kill system call can be used to send any signal to any process group or process.

If pid is positive, then signal sig is sent to pid. In this case, 0 is returned on success, or a negative value on error.

If pid equals -1, then sig is sent to every process except for the first one, from higher numbers in the proc table to lower. In this case, 0 is returned on success, or the error condition resulting from signalling the last process is returned.

If pid is less than -1, then sig is sent to every process in the process group -pid. In this case, the number of processes the signal was sent to is returned, or a negative value for failure.

RETURN VALUE
On success, zero is returned. On error, -1 is returned, and errno is set appropriately.

ERRORS

EINVAL
    An invalid signal is sent.

ESRCH
    The pid or process group does not exist. Note that an existing process might be a zombie, a process which already committed termination, but has not yet been wait()ed for.

EPERM
    The process does not have permission to send the signal to any of the receiving processes. For a process to have permission to send a signal to process pid it must either have root privileges, or the real or effective user ID of the sending process must equal the real or saved set-user-ID of the receiving process.

BUGS
It is impossible to send a signal to task number one, the init process, for which it has not installed a signal handler. This is done to assure the system is not brought down accidentally.

CONFORMING TO
SVr4, SVID, POSIX.1, X/OPEN, BSD 4.3

SEE ALSO
_exit(2), exit(2), signal(2), signal(7)