kill: Send a signal to processes
kill command sends a signal to processes, causing them
to terminate or otherwise act upon receiving the signal in some way.
Alternatively, it lists information about signals. Synopses:
kill [-s signal | --signal signal | -signal] pid… kill [-l | --list | -t | --table] [signal]…
Due to shell aliases and built-in
kill functions, using an
kill interactively or in a script may get you
different functionality than that described here. Invoke it via
env kill …) to avoid interference
from the shell.
The first form of the
kill command sends a signal to all
pid arguments. The default signal to send if none is specified
TERM’. The special signal number ‘
0’ does not denote a
valid signal, but can be used to test whether the
specify processes to which a signal could be sent.
pid is positive, the signal is sent to the process with the
pid is zero, the signal is sent to all
processes in the process group of the current process. If
is -1, the signal is sent to all processes for which the user has
permission to send a signal. If
pid is less than -1, the signal
is sent to all processes in the process group that equals the absolute
pid is not positive, a system-dependent set of system
processes is excluded from the list of processes to which the signal
If a negative
pid argument is desired as the first one, it
should be preceded by
--. However, as a common extension to
-- is not required with ‘
kill -signal -pid’. The following commands are equivalent:
kill -15 -1 kill -TERM -1 kill -s TERM -- -1 kill -- -1
The first form of the
kill command succeeds if every
argument specifies at least one process that the signal was sent to.
The second form of the
kill command lists signal information.
--list option, or the
--table option must be specified. Without any
signal argument, all supported signals are listed. The output
--list is a list of the signal names, one
per line; if
signal is already a name, the signal number is
printed instead. The output of
--table is a
table of signal numbers, names, and descriptions. This form of the
kill command succeeds if all
signal arguments are valid
and if there is no output error.
kill command also supports the
--version options. See Common options.
signal may be a signal name like ‘
HUP’, or a signal
number like ‘
1’, or an exit status of a process terminated by the
signal. A signal name can be given in canonical form or prefixed by
SIG’. The case of the letters is ignored, except for the
-signal option which must use upper case to avoid
ambiguity with lower case option letters.
See Signal specifications, for a list of supported
signal names and numbers.