kill(1) — Linux manual page


KILL(1)                       User Commands                      KILL(1)

NAME         top

       kill - terminate a process

SYNOPSIS         top

       kill  [-signal|-s signal|-p]  [-q value] [-a] [--timeout
       milliseconds signal] [--] pid|name...

       kill -l [number] | -L

DESCRIPTION         top

       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         top

       The list of processes to be signaled can be a mixture of names
       and PIDs.

           Each pid can be expressed in one of the following ways:

               where n is larger than 0. The process with PID n is

               All processes in the current process group are signaled.

               All processes with a PID larger than 1 are signaled.

               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.

           All processes invoked using this name will be signaled.

OPTIONS         top

       -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

       -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.

           Print PID(s) that will be signaled with kill along with the

       -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

           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         top

       kill has the following exit status values:



           partial success (when more than one process specified)

NOTES         top

       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         top

       Salvatore Valente <>, Karel Zak <>

       The original version was taken from BSD 4.4.

SEE ALSO         top

       bash(1), tcsh(1), sigaction(2), kill(2), sigqueue(3), signal(7)

REPORTING BUGS         top

       For bug reports, use the issue tracker at

AVAILABILITY         top

       The kill command is part of the util-linux package which can be
       downloaded from Linux Kernel Archive
       <>. This page
       is part of the util-linux (a random collection of Linux
       utilities) project. Information about the project can be found at
       ⟨⟩. If you have
       a bug report for this manual page, send it to This page was obtained from the
       project's upstream Git repository
       ⟨git://⟩ on
       2023-12-22. (At that time, the date of the most recent commit
       that was found in the repository was 2023-12-14.) If you discover
       any rendering problems in this HTML version of the page, or you
       believe there is a better or more up-to-date source for the page,
       or you have corrections or improvements to the information in
       this COLOPHON (which is not part of the original manual page),
       send a mail to

util-linux 2.39.594-1e0ad      2023-07-19                        KILL(1)

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