View all logs
sudo journalctl
Follow logs (real-time)
sudo journalctl -f
View logs for specific service
sudo journalctl -u nginx
Follow service logs
sudo journalctl -u nginx -f
View logs since boot
sudo journalctl -b
View previous boot logs
sudo journalctl -b -1
Show last N lines
sudo journalctl -n 50
Show logs since specific time
sudo journalctl --since "2024-01-01 10:00:00"
Show logs for last hour
sudo journalctl --since "1 hour ago"
Show logs for today
sudo journalctl --since today
Show logs between times
sudo journalctl --since "2024-01-01" --until "2024-01-02"
Filter by priority (error level)
sudo journalctl -p err
Levels: emerg, alert, crit, err, warning, notice, info, debug
Show kernel messages
sudo journalctl -k
Show logs from specific user
sudo journalctl _UID=1000
Check disk usage
sudo journalctl --disk-usage
Vacuum logs (keep only 100MB)
sudo journalctl --vacuum-size=100M
Vacuum by time (keep only 2 days)
sudo journalctl --vacuum-time=2d
Export logs to file
sudo journalctl -u nginx > nginx-logs.txt