Signals can be specified either by name (e.g. -HUP) or by number (e.g. -1) or by option -s.
If the command name is not regular expression (option -r) and contains a slash (/), processes executing that particular file will be selected for killing, independent of their name.
killall returns a zero return code if at least one process has been killed for each listed command, or no commands were listed and at least one process matched the -u and -Z search criteria. killall returns non-zero otherwise.
A killall process never kills itself (but may kill other killall processes).
|-e, --exact||Require an exact match for very long names. If a command name is longer than 15 characters, the full name may be unavailable (i.e. it is swapped out). In this case, killall will kill everything that matches within the first 15 characters. With -e, such entries are skipped. killall prints a message for each skipped entry if -v is specified in addition to -e,|
|-I, --ignore-case||Do case insensitive process name match.|
|-g, --process-group||Kill the process group to which the process belongs. The kill signal is only sent once per group, even if multiple processes belonging to the same process group were found.|
|-i, --interactive||Interactively ask for confirmation before killing.|
|-l, --list||List all known signal names.|
|-q, --quiet||Do not complain if no processes were killed.|
|-r, --regexp||Interpret process name pattern as an extended regular expression.|
|-s, --signal||Send this signal instead of SIGTERM.|
|-u, --user||Kill only processes the specified user owns. Command names are optional.|
|-v, --verbose||Report if the signal was successfully sent.|
|-V, --version||Display version information.|
|-w, --wait||Wait for all killed processes to die. killall checks once per second if any of the killed processes still exist and only returns if none are left. Note that killall may wait forever if the signal was ignored, had no effect, or if the process stays in zombie state.|
|-Z, --context||(SELinux Only) Specify security context: kill only processes having security context that match with given expended regular expression pattern. Must precede other arguments on the command line. Command names are optional.|
/proc location of the proc file system
Be warned that typing killall name may not have the desired effect on non-Linux systems, especially when done by a privileged user.
killall -w doesnt detect if a process disappears and is replaced by a new process with the same PID between scans.
If processes change their name, killall may not be able to match them correctly.