Pausing and resuming a process

The foreground job

Ctrl+Z sends SIGTSTP to the foreground job: frozen, memory and file descriptors kept open.

jobs            # list suspended jobs and their numbers
fg              # resume the most recent in the foreground
bg              # resume it in the background
fg %2           # resume job 2
bg %2

Anything else

Find the PID, then signal:

ps aux | grep <process_name>
pidof <process_name>
sudo kill -STOP <PID>       # or kill -SIGSTOP
sudo kill -CONT <PID>       # or kill -SIGCONT

SIGSTOP cannot be caught or ignored — reliable when you do not control the process.

In a container

Host signals do not reach a container’s process; use the runtime:

docker pause <container_id>
docker unpause <container_id>

A paused process uses no CPU but keeps its memory. SIGSTOP state is not persisted, so a suspended terminal job dies at reboot; anything that must hold across restarts needs hibernation or explicit state saving.

References

• signal(7)