Linux Signals and Job Control

long_task &

# Launch a command as a background job.

jobs -l

# Show background and stopped jobs with PIDs.

fg %1

# Resume a job in the foreground.

bg %1

# Continue a stopped job in the background.

# Press Ctrl+Z in the terminal

# Suspend the current foreground process group.

disown %1

# Prevent the shell from sending SIGHUP to the job on exit.

wait 1234

# Block until a background PID exits.

wait %1

# Block until a shell job completes.

trap "echo caught INT" INT

# Handle a signal in a shell script.

kill -- -1234

# Signal every process in a process group.

pkill -o -TERM myworker

# Signal only the oldest matching process.

pkill -n -HUP nginx

# Signal the newest matching process.

pgrep -c sshd

# Count processes that match a pattern.

pkill -USR1 myapp

# Send a custom signal to matching processes.

kill -0 1234

# Check whether a process exists and whether you can signal it.

pkill -x ssh-agent

# Only match an exact process name.

pkill -P 1234

# Signal all child processes of a parent.

killall -u alice python

# Limit killall by user and executable name.

killall -r "worker[0-9]+"

# Use a regex pattern with killall where supported.

lsof -ti :3000 | xargs -r -n1 kill -TERM

# Combine lsof and xargs to terminate port users.