x SuSE Linux 13.1-RELEASE x
x SuSE Linux 13.1-RELEASEx
KILL(1) User Commands KILL(1)
NAME
kill - terminate a process
SYNOPSIS
kill [-signal|-s signal|-p] [-q value] [-a] [--timeout milliseconds
signal] [--] pid|name...
kill -l [number] | -L
DESCRIPTION
The command kill sends the specified signal to the specified processes
or process groups.
If no signal is specified, the TERM signal is sent. The default action
for this signal is to terminate the process. This signal should be used
in preference to the KILL signal (number 9), since a process may
install a handler for the TERM signal in order to perform clean-up
steps before terminating in an orderly fashion. If a process does not
terminate after a TERM signal has been sent, then the KILL signal may
be used; be aware that the latter signal cannot be caught, and so does
not give the target process the opportunity to perform any clean-up
before terminating.
Most modern shells have a builtin kill command, with a usage rather
similar to that of the command described here. The --all, --pid, and
--queue options, and the possibility to specify processes by command
name, are local extensions.
If signal is 0, then no actual signal is sent, but error checking is
still performed.
ARGUMENTS
The list of processes to be signaled can be a mixture of names and
PIDs.
pid
Each pid can be expressed in one of the following ways:
n
where n is larger than 0. The process with PID n is signaled.
0
All processes in the current process group are signaled.
-1
All processes with a PID larger than 1 are signaled.
-n
where n is larger than 1. All processes in process group n are
signaled. When an argument of the form '-n' is given, and it is
meant to denote a process group, either a signal must be
specified first, or the argument must be preceded by a '--'
option, otherwise it will be taken as the signal to send.
name
All processes invoked using this name will be signaled.
OPTIONS
-s, --signal signal
The signal to send. It may be given as a name or a number.
-l, --list [number]
Print a list of signal names, or convert the given signal number to
a name. The signals can be found in /usr/include/linux/signal.h.
-L, --table
Similar to -l, but it will print signal names and their
corresponding numbers.
-a, --all
Do not restrict the command-name-to-PID conversion to processes
with the same UID as the present process.
-p, --pid
Only print the process ID (PID) of the named processes, do not send
any signals.
-r, --require-handler
Do not send the signal if it is not caught in userspace by the
signalled process.
--verbose
Print PID(s) that will be signaled with kill along with the signal.
-q, --queue value
Send the signal using sigqueue(3) rather than kill(2). The value
argument is an integer that is sent along with the signal. If the
receiving process has installed a handler for this signal using the
SA_SIGINFO flag to sigaction(2), then it can obtain this data via
the si_sigval field of the siginfo_t structure.
--timeout milliseconds signal
Send a signal defined in the usual way to a process, followed by an
additional signal after a specified delay. The --timeout option
causes kill to wait for a period defined in milliseconds before
sending a follow-up signal to the process. This feature is
implemented using the Linux kernel PID file descriptor feature in
order to guarantee that the follow-up signal is sent to the same
process or not sent if the process no longer exists.
Note that the operating system may re-use PIDs and implementing an
equivalent feature in a shell using kill and sleep would be subject
to races whereby the follow-up signal might be sent to a different
process that used a recycled PID.
The --timeout option can be specified multiple times: the signals
are sent sequentially with the specified timeouts. The --timeout
option can be combined with the --queue option.
As an example, the following command sends the signals QUIT, TERM
and KILL in sequence and waits for 1000 milliseconds between
sending the signals:
kill --verbose --timeout 1000 TERM --timeout 1000 KILL \
--signal QUIT 12345
EXIT STATUS
kill has the following exit status values:
0
success
1
failure
64
partial success (when more than one process specified)
NOTES
Although it is possible to specify the TID (thread ID, see gettid(2))
of one of the threads in a multithreaded process as the argument of
kill, the signal is nevertheless directed to the process (i.e., the
entire thread group). In other words, it is not possible to send a
signal to an explicitly selected thread in a multithreaded process. The
signal will be delivered to an arbitrarily selected thread in the
target process that is not blocking the signal. For more details, see
signal(7) and the description of CLONE_THREAD in clone(2).
Various shells provide a builtin kill command that is preferred in
relation to the kill(1) executable described by this manual. The
easiest way to ensure one is executing the command described in this
page is to use the full path when calling the command, for example:
/bin/kill --version
AUTHORS
Salvatore Valente <svalente@mit.edu>, Karel Zak <kzak@redhat.com>
The original version was taken from BSD 4.4.
SEE ALSO
bash(1), tcsh(1), sigaction(2), kill(2), sigqueue(3), signal(7)
REPORTING BUGS
For bug reports, use the issue tracker at
https://github.com/util-linux/util-linux/issues.
AVAILABILITY
The kill command is part of the util-linux package which can be
downloaded from Linux Kernel Archive
<https://www.kernel.org/pub/linux/utils/util-linux/>.
util-linux 2.39.3 2023-11-21 KILL(1)
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