kill - send signal to a process
#include <sys/types.h>
#include <signal.h>
int kill(pid_t pid, int sig);
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.
If pid equals 0, then sig is sent to every process in the process group
of the current process.
If pid equals -1, then sig is sent to every process except for the
first one.
If pid is less than -1, then sig is sent to every process in the
process group -pid.
If sig is 0, then no signal is sent, but error checking is still performed.
On success, zero is returned. On error, -1 is returned, and errno is
set appropriately.
EINVAL An invalid signal was specified.
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. In the case of SIGCONT it suffices when the sending
and receiving processes belong to the same session.
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.
SVr4, SVID, POSIX.1, X/OPEN, BSD 4.3
_exit(2), exit(3), signal(2), signal(7)
Linux 2.0.30 1997-09-14 KILL(2)
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