NAME
kill – terminate or signal a process
SYNOPSIS
kill [-s signal_name] pid ...
kill -l [exit_status]
kill -signal_name pid ...
kill -signal_number pid ...
DESCRIPTION
The kill utility sends a signal to the processes specified by the pid operands.
Only the super-user may send signals to other users' processes.
The options are as follows:
- -s signal_name
-
A symbolic signal name specifying the signal to be sent instead of the default TERM.
- -l [exit_status]
-
If no operand is given, list the signal names; otherwise, write the signal name corresponding to exit_status.
- -signal_name
-
A symbolic signal name specifying the signal to be sent instead of the default TERM.
- -signal_number
-
A non-negative decimal integer, specifying the signal to be sent instead of the default TERM.
The following PIDs have special meanings:
- 0
-
The signal is sent to all processes whose group ID is equal to the process group ID of the sender, and for which the process has permission.
- -1
-
If superuser, broadcast the signal to all processes; otherwise broadcast to all processes belonging to the user.
- -PGID
-
The signal is sent to all processes that belong to the specified process group ID (PGID).
Some of the more commonly used signals:
- 1
-
HUP (hang up)
- 2
-
INT (interrupt)
- 3
-
QUIT (quit)
- 6
-
ABRT (abort)
- 9
-
KILL (non-catchable, non-ignorable kill)
- 14
-
ALRM (alarm clock)
- 15
-
TERM (software termination signal)
Some shells may provide a builtin kill command which is similar or identical to this utility. Consult the builtin(1) manual page.
EXIT STATUS
The kill utility exits 0 on success, and >0 if an error occurs.
EXAMPLES
Terminate the processes with PIDs 142 and 157:
kill 142 157
Send the hangup signal (SIGHUP) to the process with PID 507:
kill -s HUP 507
Terminate the process group with PGID 117:
kill -- -117
SEE ALSO
builtin(1), csh(1), killall(1), ps(1), sh(1), kill(2), sigaction(2)
STANDARDS
The kill utility is expected to be IEEE Std 1003.2 (“POSIX.2”) compatible.
HISTORY
A kill command appeared in Version 3 AT&T UNIX in section 8 of the manual.
BUGS
A replacement for the command “kill 0” for csh(1) users should be provided.