Linux Process Management Cheat Sheet¶

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Überblick¶

Linux Prozessmanagement beinhaltet die Überwachung, Steuerung und Optimierung von laufenden Prozessen und Systemressourcen. Dieser umfassende Leitfaden umfasst Prozessüberwachungstools, Signalhandling, Jobsteuerung, Systemressourcenmanagement und Leistungsoptimierungstechniken, die für Systemadministratoren und IT-Profis unerlässlich sind.

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Prozessansicht und Überwachung¶

Grundlegende Prozessinformationen¶

```bash

Display running processes¶

ps ps aux # All processes with detailed info ps -ef # Full format listing ps -u username # Processes for specific user ps -p PID # Specific process by PID

Process tree view¶

pstree pstree -p # Show PIDs pstree username # Processes for specific user

Real-time process monitoring¶

top htop # Enhanced interactive process viewer ```_

Erweiterte Prozessüberwachung¶

```bash

Detailed process information¶

ps auxf # Process tree format ps -eo pid,ppid,cmd,pcpu,pmem # Custom columns

Process by resource usage¶

ps aux --sort=-pcpu # Sort by CPU usage ps aux --sort=-pmem # Sort by memory usage

Long-running processes¶

ps -eo pid,etime,cmd # Show elapsed time

Zombie processes¶

ps aux|grep -w Z ps -eo stat,pid,cmd|grep -w Z ```_

Echtzeit-Systemüberwachung¶

```bash

Interactive process monitor¶

top

Top commands:¶

k - kill process¶

r - renice process¶

M - sort by memory¶

P - sort by CPU¶

q - quit¶

Enhanced process monitor¶

htop

htop features:¶

F9 - kill process¶

F7/F8 - nice/renice¶

F6 - sort options¶

F10 - quit¶

System activity reporter¶

sar -u 1 10 # CPU usage every 1 second, 10 times sar -r 1 10 # Memory usage sar -d 1 10 # Disk activity ```_

Prozesssteuerung und Signale¶

Signaltypen¶

```bash

Common signals:¶

SIGTERM (15) - Graceful termination¶

SIGKILL (9) - Force kill (cannot be caught)¶

SIGHUP (1) - Hangup (reload config)¶

SIGSTOP (19) - Stop process¶

SIGCONT (18) - Continue stopped process¶

SIGINT (2) - Interrupt (Ctrl+C)¶

```_

Killing Processes¶

```bash

Kill by PID¶

kill PID kill -15 PID # Send SIGTERM (default) kill -9 PID # Force kill with SIGKILL kill -HUP PID # Send hangup signal

Kill by process name¶

killall process_name killall -9 process_name

Kill by pattern¶

pkill pattern pkill -f pattern # Match full command line pkill -u username # Kill user's processes

Interactive process killer¶

top # Press 'k' then enter PID htop # Press F9 then select process ```_

Prozesspriorität und Nizza Werte¶

```bash

View process priorities¶

ps -eo pid,ni,cmd

Start process with specific priority¶

nice -n 10 command # Lower priority (+10) nice -n -5 command # Higher priority (-5)

Change running process priority¶

renice 10 PID # Set nice value to 10 renice -5 -p PID # Set nice value to -5 renice 5 -u username # Renice all user processes ```_

Job Control¶

Hintergrund und Vordergrund Jobs¶

```bash

Run command in background¶

command &

List active jobs¶

jobs jobs -l # Show PIDs

Bring job to foreground¶

fg fg %1 # Bring job 1 to foreground

Send job to background¶

bg bg %1 # Send job 1 to background

Suspend current job¶

Ctrl+Z

Resume suspended job¶

fg # Resume in foreground bg # Resume in background ```_

Dauerhafte Prozesse¶

```bash

Run command immune to hangups¶

nohup command & nohup command > output.log 2>&1 &

Detach from terminal¶

disown %1 # Disown job 1 disown -a # Disown all jobs

Screen sessions¶

screen # Start new session screen -S name # Named session screen -r # Reattach to session screen -ls # List sessions

Tmux sessions¶

tmux # Start new session tmux new -s name # Named session tmux attach -t name # Attach to session tmux list-sessions # List sessions ```_

Systemressourcenüberwachung¶

CPU Überwachung¶

```bash

CPU usage overview¶

top htop vmstat 1 # Virtual memory statistics iostat 1 # I/O and CPU statistics

Per-CPU statistics¶

mpstat # Multi-processor statistics mpstat -P ALL 1 # All CPUs every second

CPU load averages¶

uptime w # Who is logged in and load cat /proc/loadavg # Load average file ```_

Speicherüberwachung¶

```bash

Memory usage¶

free free -h # Human readable free -m # In megabytes free -s 1 # Update every second

Detailed memory information¶

cat /proc/meminfo vmstat 1 # Virtual memory stats

Memory usage by process¶

ps aux --sort=-pmem|head -10 top -o %MEM # Sort by memory in top

Memory map of process¶

pmap PID pmap -d PID # Detailed mapping ```_

Disk I/O Monitoring¶

```bash

Disk usage¶

df -h # Filesystem usage du -sh /path # Directory usage

I/O statistics¶

iostat iostat -x 1 # Extended stats every second iotop # Real-time I/O monitoring

Disk activity by process¶

iotop -o # Only show active processes pidstat -d 1 # Per-process I/O stats ```_

Netzwerküberwachung¶

```bash

Network connections¶

netstat -tuln # TCP/UDP listening ports ss -tuln # Modern replacement for netstat ss -p # Show process names

Network activity¶

netstat -i # Interface statistics iftop # Real-time network usage nethogs # Network usage by process

Network connections by process¶

lsof -i # Network files lsof -i :80 # Processes using port 80 ```_

Prozessanalyse und Debugging¶

Informationen zum Thema¶

```bash

Detailed process info¶

cat /proc/PID/status cat /proc/PID/cmdline cat /proc/PID/environ

Process file descriptors¶

lsof -p PID ls -la /proc/PID/fd/

Process memory maps¶

cat /proc/PID/maps pmap PID

Process threads¶

ps -T -p PID top -H -p PID ```_

Systemanrufe und Debugging¶

```bash

Trace system calls¶

strace command strace -p PID # Attach to running process strace -f command # Follow forks

Library calls¶

ltrace command ltrace -p PID

Debug running process¶

gdb -p PID ```_

Leistungsanalyse¶

```bash

Process CPU usage over time¶

pidstat 1 # Per-process statistics pidstat -p PID 1 # Specific process

Memory usage tracking¶

pidstat -r 1 # Memory statistics pidstat -d 1 # Disk I/O statistics

System performance overview¶

vmstat 1 10 # Virtual memory stats sar -A # All system activity ```_

Systemdienstleistungen und Daemons¶

Systemisches Servicemanagement¶

```bash

Service status¶

systemctl status service_name systemctl is-active service_name systemctl is-enabled service_name

Start/stop services¶

systemctl start service_name systemctl stop service_name systemctl restart service_name systemctl reload service_name

Enable/disable services¶

systemctl enable service_name systemctl disable service_name

List services¶

systemctl list-units --type=service systemctl list-units --failed ```_

Service Logs¶

```bash

View service logs¶

journalctl -u service_name journalctl -u service_name -f # Follow logs journalctl -u service_name --since today

System logs¶

journalctl journalctl -f # Follow system logs journalctl --since "1 hour ago" journalctl -p err # Error messages only ```_

Prozessautomatisierung und -planung¶

Cron Jobs¶

```bash

Edit crontab¶

crontab -e crontab -l # List cron jobs crontab -r # Remove all cron jobs

System cron directories¶

ls /etc/cron.d/ ls /etc/cron.daily/ ls /etc/cron.hourly/ ls /etc/cron.weekly/ ls /etc/cron.monthly/

Cron log¶

tail -f /var/log/cron ```_

Bei Jobs (Einmalige Planung)¶

```bash

Schedule one-time job¶

at 15:30 at now + 1 hour at tomorrow

List scheduled jobs¶

atq at -l

Remove scheduled job¶

atrm job_number ```_

Probleme bei der Fehlerbehebung¶

Hohe CPU Verwendung¶

```bash

Find CPU-intensive processes¶

top -o %CPU ps aux --sort=-pcpu|head -10

CPU usage by command¶

pidstat -u 1

System load investigation¶

uptime vmstat 1 sar -u 1 10 ```_

Hohe Speichernutzung¶

```bash

Memory-intensive processes¶

ps aux --sort=-pmem|head -10 top -o %MEM

Memory leaks detection¶

valgrind --leak-check=full command

Out of memory investigation¶

dmesg|grep -i "killed process" grep -i "out of memory" /var/log/messages ```_

Zombie Prozesse¶

```bash

Find zombie processes¶

ps aux|awk '$8 ~ /^Z/ \\{ print $2 \\}' ps -eo stat,pid,cmd|grep -w Z

Kill parent of zombie¶

ps -o ppid= -p zombie_pid kill parent_pid ```_

Prozess nicht reagieren¶

```bash

Check if process is hung¶

kill -0 PID # Test if process exists strace -p PID # See what process is doing

Force termination¶

kill -TERM PID # Try graceful first sleep 5 kill -KILL PID # Force if necessary ```_

Leistungsoptimierung¶

Prozessbeschränkungen¶

```bash

View current limits¶

ulimit -a cat /proc/PID/limits

Set limits¶

ulimit -n 4096 # File descriptors ulimit -u 1024 # Max user processes ulimit -m 1048576 # Memory limit (KB)

System-wide limits¶

cat /etc/security/limits.conf ```_

CPU Affinität¶

```bash

View CPU affinity¶

taskset -p PID

Set CPU affinity¶

taskset -p 0x1 PID # CPU 0 only taskset -p 0x3 PID # CPU 0 and 1 taskset -c 0,1 PID # CPU 0 and 1

Start process with affinity¶

taskset -c 0 command ```_

Ressourcen¶

[Linux Process Management Guide](LINK_4_
Systemd Dokumentation
(LINK_4_)
(LINK_4_)

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*Dieses Cheatsheet bietet umfassende Prozessmanagement-Befehle für Linux-Systeme. Verstehen Sie immer die Auswirkungen von Prozesssteuerungsbefehlen, bevor Sie sie in Produktionsumgebungen verwenden. *