killall --version (return code: 0)
killall (PSmisc) 22.21 Copyright (C) 1993-2012 Werner Almesberger and Craig Small PSmisc comes with ABSOLUTELY NO WARRANTY. This is free software, and you are welcome to redistribute it under the terms of the GNU General Public License. For more information about these matters, see the files named COPYING.
killall --help (return code: 1)
Usage: killall [-Z CONTEXT] [-u USER] [ -eIgiqrvw ] [ -SIGNAL ] NAME... killall -l, --list killall -V, --version -e,--exact require exact match for very long names -I,--ignore-case case insensitive process name match -g,--process-group kill process group instead of process -y,--younger-than kill processes younger than TIME -o,--older-than kill processes older than TIME -i,--interactive ask for confirmation before killing -l,--list list all known signal names -q,--quiet don't print complaints -r,--regexp interpret NAME as an extended regular expression -s,--signal SIGNAL send this signal instead of SIGTERM -u,--user USER kill only process(es) running as USER -v,--verbose report if the signal was successfully sent -V,--version display version information -w,--wait wait for processes to die -Z,--context REGEXP kill only process(es) having context (must precede other arguments)