killall Command Cheat Sheet

killall sends a signal to all processes running any of the specified commands. It is handy when multiple instances of a program are running (e.g., chrome, httpd).

⚠️ Warning: On some Unix systems (like Solaris/AIX), killall kills ALL processes on the system (Shutdown). On Linux, it kills by name.

Synopsis

killall [OPTIONS] [NAME...]

Basic Usage

Terminate All Instances

Terminates all processes named firefox.

killall firefox

Force Kill All Instances

killall -9 firefox

Or:

killall -SIGKILL firefox

Targeting Specifics

By User (-u)

Kill only nginx processes owned by www-data.

sudo killall -u www-data nginx

By Time (Younger/Older)

Kill processes running for less than 30 minutes.

killall -y 30m infinite_loop_script

Kill processes running for more than 1 week.

killall -o 1w obsolete_daemon

Units: s(econds), m(inutes), h(ours), d(ays), w(eeks), M(onths), y(ears).

Interactive & Safety

Interactive Mode (-i)

Ask for confirmation before killing each process.

killall -i firefox
# Output: Kill firefox(1234) ? (y/N)

Dry Run (Verbose)

Use -v to report if the signal was sent successfully. killall doesn't strictly have a "dry run" flag like make, but standard practice to check what would match is using pgrep -a name.

However, killall -v shows what happens:

killall -v firefox
# Output: Killed firefox(1234) with signal 15

Regex Matching (-r)

Interpret the process name pattern as an extended regular expression.

# Kill all processes starting with "php"
killall -r "^php"

Exit Status

Code	Meaning
0	Success (at least one process killed)
1	No matching process found

Comparison: killall vs pkill

Feature	`killall`	`pkill`
Match by	Exact Name (default)	Pattern / Partial (default)
Regex	Yes (-r)	Yes (default)
Interactive	Yes (-i)	No
Package	psmisc	procps

Notes

Exact Match: By default, killall apache will NOT kill apache2. It requires an exact match.
Process Group: Unlike kill, killall operates on names, not PIDs or Job IDs.