kill

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.

       --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/karelzak/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 2.37.2                  2021-06-02                            KILL(1)