View Source: kill(2) - Waikato Linux Users Group

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!!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(2) 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.  This is an excellent way to see if a process is still running, send it signal 0, then check to see if you got [ESRCH] as an error.

!!RETURN VALUE
On success, zero is returned. On error, -1 is returned, and ''errno'' is set appropriately.
!!ERRORS
;[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 [wait4(2)]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.

!!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(3), signal(2), signal(7)

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Last edited on Thursday, February 20, 2003 11:28:40 pm by PerryLorier

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