Processes & System Monitoring¶

ps                       # processes in current shell
ps aux                   # all processes (detailed)
ps -ef | grep nginx      # filter processes by name
pgrep -af python         # find PIDs by pattern

top                      # live process viewer (q to quit)
htop                     # interactive viewer (if installed)

kill 12345               # graceful stop (SIGTERM)
kill -9 12345            # force stop (SIGKILL)
pkill -f "uvicorn"       # kill by command pattern
killall node             # kill all by exact name

long_task &              # start command in background
jobs                     # list background jobs
fg %1                    # bring job 1 to foreground
bg %1                    # resume stopped job in background

watch -n 5 'df -h'       # run df -h every 5 seconds
watch -n 2 'ps aux | head -20'  # watch top processes

systemctl status nginx   # check if service is running
systemctl start nginx    # start service
systemctl stop nginx     # stop service
systemctl restart nginx  # restart service
systemctl enable nginx   # start on boot
systemctl disable nginx  # do not start on boot
systemctl list-units --failed  # show failed services

journalctl -u nginx -n 100   # last 100 log lines for service
journalctl -u nginx -f       # follow logs live
journalctl -p err             # show only errors and above

who                      # show who is logged in
w                        # show logged-in users + their activity

free -h                  # RAM usage (human-readable)
df -h                    # disk usage by filesystem
du -sh ./*               # size of each item in current dir
du -sh /var/log          # size of specific directory
lsblk                    # list block devices (disks/partitions)
uptime                   # uptime + load average
uname -a                 # kernel info
hostname                 # show system hostname
lscpu                    # CPU info (cores, model, cache)
vmstat 1 5               # virtual memory stats (1s interval, 5 times)
cat /etc/os-release      # distribution info