How to Manage Processes in Linux

Viewing Processes

To list running processes:

ps aux

For a live view of system activity:

top

Or a more modern interactive tool:

htop

(Install htop on Debian/Ubuntu with sudo apt install htop, or on CentOS/AlmaLinux with sudo yum install htop.)

Stopping Processes

Kill a process by its PID:

kill 1234

Force kill:

kill -9 1234

Kill all instances of a program:

pkill firefox

Managing Services with systemctl

# check status
sudo systemctl status nginx

# start service
sudo systemctl start nginx

# stop service
sudo systemctl stop nginx

# restart service
sudo systemctl restart nginx

# enable on boot
sudo systemctl enable nginx

Changing Process Priority

Use nice to start a process with priority:

nice -n 10 myscript.sh

Use renice to adjust a running process:

renice -n 5 -p 1234

Running Processes in Background

# run in background
command &

# bring job to foreground
fg %1

# show background jobs
jobs