kill

KILL(1)                          User Commands                         KILL(1)



NAME
       kill - terminate a process

SYNOPSIS
       kill [-signal|-s signal|-p] [-q value] [-a] [--] 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 one of four things:

              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
              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.


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).


RETURN CODES
       kill has the following return codes:

       0      success

       1      failure

       64     partial success (when more than one process specified)


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


AUTHORS
       Salvatore Valente ⟨svalente@mit.edu⟩
       Karel Zak ⟨kzak@redhat.com⟩

       The original version was taken from BSD 4.4.


AVAILABILITY
       The kill command is part of the util-linux package and is available
       from Linux Kernel Archive ⟨https://www.kernel.org/pub/linux/utils/util-
       linux/⟩.



util-linux                         July 2014                           KILL(1)