Process Management on Linux

Viewing Processes

# All processes with full details
ps aux

# Tree view (shows parent-child relationships)
ps auxf

# Filter by name
ps aux | grep nginx

# Real-time monitoring
top
htop  # More user-friendly (install: apt install htop)

Process Signals

# Graceful termination
kill PID
kill -SIGTERM PID

# Force kill (last resort)
kill -9 PID
kill -SIGKILL PID

# Kill all processes by name
killall nginx
pkill -f "python script.py"

Background and Foreground

# Run in background
./long-script.sh &

# Move running process to background
# Press Ctrl+Z to suspend, then:
bg

# Bring back to foreground
fg

# List background jobs
jobs

Process Priority

# Run with lower priority (higher nice value = lower priority)
nice -n 19 ./heavy-task.sh

# Change priority of running process
renice -n 10 -p PID

Persistent Processes

Keep processes running after logout:

# Using nohup
nohup ./script.sh > output.log 2>&1 &

# Using screen
screen -S mysession
./long-running-task.sh
# Press Ctrl+A, D to detach
screen -r mysession  # Reattach

# Using tmux
tmux new -s mysession
./long-running-task.sh
# Press Ctrl+B, D to detach
tmux attach -t mysession