Bash Script to Find and Kill Process by Name

Use pkill -f process_name to find and kill a process by name in Bash, or use kill $(pgrep -f process_name) for more control.

Examples

Inputprocess_name=firefox

OutputAll running Firefox processes are terminated.

Inputprocess_name=nonexistentprocess

OutputNo processes found; no action taken.

Inputprocess_name=python

OutputAll Python processes are terminated.

How to Think About It

To find and kill a process by name, first identify all running processes matching the name, then send a termination signal to each. This can be done by searching process names and using their process IDs to kill them.

Algorithm

1

Get the process name as input.

2

Search for all process IDs matching the name.

3

If no process is found, exit or notify.

4

Send a kill signal to each found process ID.

5

Confirm the processes are terminated.

Code

bash

#!/bin/bash

process_name="$1"

if [ -z "$process_name" ]; then
  echo "Usage: $0 process_name"
  exit 1
fi

pids=$(pgrep -f "$process_name")

if [ -z "$pids" ]; then
  echo "No process found with name '$process_name'."
  exit 0
fi

echo "Killing processes with name '$process_name':"
for pid in $pids; do
  echo "Killing PID $pid"
  kill "$pid"
done

Output

Killing processes with name 'firefox':
Killing PID 12345
Killing PID 12346

Dry Run

Let's trace killing 'firefox' processes through the code

1

Get process name

process_name='firefox'

2

Find PIDs

pids='12345 12346'

3

Kill each PID

kill 12345 kill 12346

Step	Process Name	PIDs Found	Action
1	firefox		Read input
2	firefox	12345 12346	Find PIDs with pgrep
3	firefox	12345	kill 12345
4	firefox	12346	kill 12346

Why This Works

Step 1: Find process IDs

The script uses pgrep -f to find all process IDs matching the given name, including full command lines.

Step 2: Check if processes exist

If no matching processes are found, the script exits gracefully without errors.

Step 3: Kill each process

The script loops over each found PID and sends a kill signal to terminate the process.

Alternative Approaches

Using pkill

bash

#!/bin/bash
process_name="$1"
if [ -z "$process_name" ]; then
  echo "Usage: $0 process_name"
  exit 1
fi

pkill -f "$process_name" && echo "Killed all '$process_name' processes." || echo "No process found."

Simpler and faster but less control over individual PIDs.

Using ps and grep

bash

#!/bin/bash
process_name="$1"
if [ -z "$process_name" ]; then
  echo "Usage: $0 process_name"
  exit 1
fi

pids=$(ps aux | grep "$process_name" | grep -v grep | awk '{print $2}')
if [ -z "$pids" ]; then
  echo "No process found with name '$process_name'."
  exit 0
fi
for pid in $pids; do
  kill "$pid"
done

More manual and less efficient, but works on systems without pgrep/pkill.

Complexity: O(n) time, O(n) space

Time Complexity

The script scans all running processes once to find matches, so time grows linearly with the number of processes.

Space Complexity

It stores matching process IDs in memory, which grows with the number of matches but is usually small.

Which Approach is Fastest?

Using pkill is fastest and simplest, while ps | grep is slower and more manual.

Approach	Time	Space	Best For
pgrep + kill loop	O(n)	O(n)	Control over each PID
pkill	O(n)	O(1)	Quick kill by name
ps + grep + kill	O(n)	O(n)	Systems without pgrep/pkill