Linux / Unix: killall Command Examples

I am a new Linux and Unix user and sysadmin. How do I kill processes by name instead by PID on Linux or Unix-like systems?

The kill command kills process by PID (process ID). To kill process by name, use killall command.

killall command details
Description	Kill processes by name
Category	Processes Management
Difficulty	Intermediate
Root privileges	No
Estimated completion time	10m
Contents Syntax Unix/Linux signal names Examples Kill process owned by specific user Kill process running on specific tty Kill process group Confirm process killing Kill process by time Option Video See also

Please note that killall command on AIX/Solairs/HP-UX and few other traditional Unix operating systems cancels all processes except the calling process i.e. it terminate all active processes. The command discussed here is about killing process by name and tested on the following platforms only:

Linux
Apple OS X Unix
FreeBSD

Purpose

Kill process or commands by name on Linux/FreeBSD/Apple OS X Unix.

Syntax

The basic syntax is as follows:

killall process
OR
killall -SIGNAL process
OR
killall command
OR
killall -15 command
OR
killall -u {userName} processName
OR
killall -t {ttyName} processName
OR
killall [options] processName

Understanding Linux and Unix signals

To display list of all known signal names, enter:

$ killall -l

Sample outputs:

HUP INT QUIT ILL TRAP ABRT IOT BUS FPE KILL USR1 SEGV USR2 PIPE ALRM TERM
STKFLT CHLD CONT STOP TSTP TTIN TTOU URG XCPU XFSZ VTALRM PROF WINCH IO PWR SYS
UNUSED

By default SIGTERM/TERM (15) is sent to process, if not signal is given to the killall command. The following signals are usefully used by both users and sysadmins:

Signal name	Numeric value	Description
SIGHUP HUP	1	Hangup detected on controlling terminal. Use this to reload server after updating its config files.
SIGINT INT	2	Interrupt from keyboard.
SIGQUIT QUIT	3	Tell command to quit.
SIGKILL KILL	9	Kill running process. This single cannot be blocked by process and must be used as a last resort to kill process. The KILL signal doesn’t allow a process to exit gracefully.
SIGTERM TERM	15	Kill running process gracefully i.e. close all files and exit cleanly. This is a default signal.
SIGSTOP STOP	19	Stop/suspend running process.
SIGCONT CONT	18	Continue process if stopped/suspended.

You can kill your own process. To kill all other users process you need to the privileged root user.

killall command examples

In this example, start a process called xeyes as follows:
$ xeyes &
Sample outputs:

[1] 3514

To kill xeyes process, type:
$ killall xeyes
OR Send a signal as a name:
$ killall -TERM xeyes
OR send a signal numerically:
$ killall -15 xeyes
Sample outputs:

[1]+  Terminated              xeyes

To get more verbose output on screen pass the -v option:
$ killall -v -TERM xeyes
Sample outputs:

Killed xeyes(4279) with signal 15
[1]+  Terminated              xeyes

How do I kill process owned by the specific user?

The syntax is as follows:
killall -u {user} process
To kill php-cgi process owned by nixcraft, user:
# killall -u nixcraft php-cgi
OR
# killall -TERM -u nixcraft php-cgi
OR
# killall -KILL -u nixcraft php-cgi

How do I kill process running on specific tty?

To show the name the terminal use tty command:
$ tty
Sample outputs:

/dev/pts/0

You can also use ps command or w command to display tty:
$ ps $ w
The syntax is as follows to kill firefox process running pts/0:
killall -t pts/0 firefox
OR
killall -t pts/0 firefox
OR
killall -t pts/0 firefox
OR combine both username and tty as follows:
# killall -u nixcraft -t pts/0 firefox

Kill process group

In this example, kill process group called php-cgi instead of process name:
$ sudo killall -KILL -v -g php-cgi
Sample outputs:

The kill signal is only sent once per group, even if multiple processes belonging to the same process group were found.

Confirm process killing

The killall command can ask for interactive confirmation before killing process by passing the -i option as follows:
$ killall -i gedit
Sample outputs:

Kill process by given time

Pass the -y TIME option to kill processes younger than given TIME. Pass the -o TIME option to kill processes older than given TIME. TIME can be expressed in the following float format then the unit:

s for seconds
m for minutes
h for hours
d for days
w for weeks
M for Months
y for years

Here are some examples for timely process killing:

# Kill firefox command younger than 3 days
killall -y 3d  firefox
 
# Kill top command  younger than 2 minutes
killall -y 2m  firefox
 
# Kill perl-cgi command older than 1 months
killall -o 1M  perl
 
# Kill nginx server older than 2 years
killall -o 2y  nginx
 
# Kill ping command  older than 2 weeks with confirmation and owned by vivek user
killall -u vivek -i -o 2w  ping

killall command options

From the killall(1) command man page:

Option	Meaning
`-e`	Require exact match for very long names.
`-I`	Case insensitive process name match.
`-g`	Kill process group instead of process.
`-y`	Kill processes younger than TIME.
`-o`	Kill processes older than TIME.
`-i`	Ask for confirmation before killing.
`-l`	List all known signal names.
`-q`	Don’t print complaints.
`-r`	Interpret NAME as an extended regular expression.
`-s`	Send this signal instead of SIGTERM.
`-u`	Kill only process(es) running as USER.
`-v`	Report if the signal was successfully sent.
`-V`	Display version information.
`-w`	Wait for processes to die.

Related media

This tutorial is also available in a quick video format:

Posted by: Vivek Gite

The author is the creator of nixCraft and a seasoned sysadmin and a trainer for the Linux operating system/Unix shell scripting. He has worked with global clients and in various industries, including IT, education, defense and space research, and the nonprofit sector. Follow him on Twitter, Facebook, Google+.