kill — Send signals to processes


kill [-f] [-signal] [-s signal] pid...

kill -l signal | -L

kill -h | -V


 -f, --force     force, using win32 interface if necessary
 -l, --list      print a list of signal names
 -L, --table     print a formatted table of signal names
 -s, --signal    send signal (use kill --list for a list)
 -W, --winpid    specified pids are windows PIDs, not Cygwin PIDs
                 (use with extreme caution!)
 -h, --help      output usage information and exit
 -V, --version   output version information and exit


The kill program allows you to send arbitrary signals to other Cygwin programs. The usual purpose is to end a running program from some other window when ^C won't work, but you can also send program-specified signals such as SIGUSR1 to trigger actions within the program, like enabling debugging or re-opening log files. Each program defines the signals they understand.

You may need to specify the full path to use kill from within some shells, including bash, the default Cygwin shell. This is because bash defines a kill builtin function; see the bash man page under BUILTIN COMMANDS for more information. To make sure you are using the Cygwin version, try

$ /bin/kill --version

which should give the Cygwin kill version number and copyright information.

The -f option uses Windows functions to terminate processes forcefully. Use -f to terminate native Windows processes not started by Cygwin processes. -f can also be useful to terminate Cygwin processes not answering to SIGKILL.

Unless you specific the -W option, the "pid" values used by kill are the Cygwin pids, not the Windows pids. To get a list of running programs and their Cygwin pids, use the Cygwin ps program. ps -W will display all windows pids.

The kill -l option prints the name of the given signal, or a list of all signal names if no signal is given.

The kill -L option is similar to -l, but it will print signal names and their corresponding numbers.

To send a specific signal, use the -signN option, either with a signal number or a signal name (minus the "SIG" part), as shown in these examples:

Example 3.7. Using the kill command

$ kill 123
$ kill -1 123
$ kill -HUP 123
$ kill -f 123

Here is a list of available signals, their numbers, and some commentary on them, from the file <sys/signal.h>, which should be considered the official source of this information.

SIGHUP       1    hangup
SIGINT       2    interrupt
SIGQUIT      3    quit
SIGILL       4    illegal instruction (not reset when caught)
SIGTRAP      5    trace trap (not reset when caught)
SIGABRT      6    used by abort
SIGIOT       6    another name for SIGABRT
SIGEMT       7    EMT instruction
SIGFPE       8    floating point exception
SIGKILL      9    kill (cannot be caught or ignored)
SIGBUS      10    bus error
SIGSEGV     11    segmentation violation
SIGSYS      12    bad argument to system call
SIGPIPE     13    write on a pipe with no one to read it
SIGALRM     14    alarm clock
SIGTERM     15    software termination signal from kill
SIGURG      16    urgent condition on IO channel
SIGSTOP     17    sendable stop signal not from tty
SIGTSTP     18    stop signal from tty
SIGCONT     19    continue a stopped process
SIGCHLD     20    to parent on child stop or exit
SIGCLD      20    System V name for SIGCHLD
SIGTTIN     21    to readers pgrp upon background tty read
SIGTTOU     22    like TTIN for output if (tp->t_local&LTOSTOP)
SIGIO       23    input/output possible
SIGPOLL     23    System V name for SIGIO
SIGXCPU     24    exceeded CPU time limit
SIGXFSZ     25    exceeded file size limit
SIGVTALRM   26    virtual time alarm
SIGPROF     27    profiling time alarm
SIGWINCH    28    window changed
SIGLOST     29    resource lost (eg, record-lock lost)
SIGPWR      29    power failure
SIGUSR1     30    user defined signal 1
SIGUSR2     31    user defined signal 2