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

       pid    Each pid can be one of four things:

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

              0      All processes in the current process group are

              -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         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 /usr/include/

       -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.

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

       -q, --queue value
              Use 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 the usual way to a process.  --timeout
              will make kill to wait for a period defined in milliseconds
              before sending follow-up signal to process.  This feature is
              implemented by PID file-descriptor and guaranties that follow-
              up signals are sent to the same process or not sent if the
              process no more exist.  Note that the operating system may re-
              use PIDs and implement the same feature in a shell by kill and
              sleep commands sequence may introduce a race.  This option can
              be specified more than once than signals are sent sequentially
              in defined timeouts.  The --timeout option can be combined
              with --queue option.

              Example.  Send signals QUIT, TERM and KILL in sequence and
              wait for 1000 milliseconds between the signals
              kill --verbose --timeout 1000 TERM --timeout 1000 KILL
              --signal QUIT 12345

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).

RETURN CODES         top

       kill has the following return codes:

       0      success

       1      failure

       64     partial success (when more than one process specified)

SEE ALSO         top

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

AUTHORS         top

       Salvatore Valente ⟨⟩
       Karel Zak ⟨⟩

       The original version was taken from BSD 4.4.

AVAILABILITY         top

       The kill command is part of the util-linux package and is available
       from Linux Kernel Archive 

COLOPHON         top

       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
       2020-02-08.  (At that time, the date of the most recent commit that
       was found in the repository was 2020-02-05.)  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                      November 2019                        KILL(1)

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