pkill -P: Kill Child Processes by Parent PID in Linux

Killing the parent does not necessarily stop its children. pkill -P lets you target the parent's direct child processes instead.

Quick answer

To send SIGTERM to every direct child of a parent process:

pkill -P PARENT_PID .

Here:

• pkill sends a signal to matching processes.
• -P PARENT_PID limits the match to processes whose direct parent is PARENT_PID.
• . is the required name pattern and matches any process name.
• Because no signal is specified, pkill sends SIGTERM.

Find child processes of a parent PID

Every process row includes a parent PID (PPID). Direct children of the same parent share that value.

Start a parent shell with three background sleep workers so you have a concrete example to inspect:

bash -c 'sleep 300 & sleep 300 & sleep 300; wait' &
PARENT=$!
sleep 1

List direct children of that parent:

ps -o pid,ppid,cmd --ppid "$PARENT" --no-headers

Sample output:

10145   10143 sleep 300
  10146   10143 sleep 300
  10147   10143 sleep 300

Each PPID column value should match $PARENT. For more ps filters, see the ps command cheat sheet.

Kill direct child processes with pkill -P

Signal every direct child of the parent from the example above:

pkill -e -P "$PARENT" .

-P "$PARENT" restricts the match to processes whose parent PID is $PARENT. . is the required name pattern and matches any process name among those children. With no signal name on the command line, pkill sends SIGTERM.

-e (--echo) prints the process name and PID of each match. It still sends the signal; it is not a preview or dry run.

Sample output:

sleep killed (pid 10145)
sleep killed (pid 10146)
sleep killed (pid 10147)

Check whether the parent still has direct children:

ps -o pid --ppid "$PARENT" --no-headers

If the command prints no rows, the parent currently has no direct child processes left.

When SIGTERM is not enough, force-kill the same direct-child set:

pkill -KILL -P "$PARENT" .

-KILL is the signal name beginners can read directly; -9 is the numeric equivalent. Use force-kill only after a normal SIGTERM stop fails. For other signals and name-based pkill, see the kill and pkill cheat sheet.

Use pkill -P with the current shell PID

Inside a Bash script, $$ is the PID of the current shell or script. Combine it with -P and . to signal every direct child of that script:

#!/bin/bash
cleanup() {
    pkill -P "$$" .
}
trap cleanup EXIT

long_running_task &
helper_task &
wait

When the script exits, the EXIT trap runs pkill -P "$$" .:

• $$ — PID of the current shell or script
• -P "$$" — restrict matches to its direct children
• . — match any process name
• no signal specified — SIGTERM by default

That works when those children still list the script as their parent at cleanup time. For Ctrl+C and more complex signal handling, see Bash trap Ctrl+C.

Common problems

References

• pkill(1)
• ps(1)
• kill(1)

Summary

Use pkill -P PARENT_PID . when you need to signal every direct child of one parent without matching unrelated processes elsewhere. pkill always needs a name pattern; -P adds the parent filter; . selects all names among those children; the default signal is SIGTERM.

List direct children first with ps --ppid when you want to confirm what will be affected. In a simple Bash script, pkill -P "$$" . on an EXIT trap is a convenient way to stop direct child workers before the interpreter exits. Remember that -P does not reach grandchildren — only the immediate children of the PID you pass.