kill (2)
NAME
kill - send signal to a processSYNOPSIS
#include <sys/types.h> #include <signal.h>
int kill(pid_t pid, int sig);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
kill(): _POSIX_C_SOURCE
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 the process with the ID specified by pid. If pid equals 0, then sig is sent to every process in the process group of the calling process. If pid equals -1, then sig is sent to every process for which the calling process has permission to send signals, except for process 1 ( init), but see below. If pid is less than -1, then sig is sent to every process in the process group whose ID is -pid. If sig is 0, then no signal is sent, but existence and permission checks are still performed; this can be used to check for the existence of a process ID or process group ID that the caller is permitted to signal. For a process to have permission to send a signal, it must either be privileged (under Linux: have the CAP_KILL capability in the user namespace of the target process), or the real or effective user ID of the sending process must equal the real or saved set-user-ID of the target process. In the case of SIGCONT, it suffices when the sending and receiving processes belong to the same session. (Historically, the rules were different; see NOTES.)RETURN VALUE
On success (at least one signal was sent), zero is returned. On error, -1 is returned, and errno is set appropriately.ERRORS
- EINVAL
- An invalid signal was specified.
- EPERM
- The process does not have permission to send the signal to any of the target processes.
- ESRCH
- The process or process group does not exist. Note that an existing process might be a zombie, a process that has terminated execution, but has not yet been wait(2)ed for.