This guide explains how to use two essential Linux troubleshooting tools:
systemctl — used for managing services (start, stop, restart, check status).
journalctl — used for viewing and analyzing system logs.
Commonly used commands
systemctl status service_name
systemctl restart service_name
systemctl enable service_name
journalctl -u service_name
journalctl -fjournalctl -xeu service_name
Below, we will take a closer look at the tools and commands mentioned.
1. What is systemctl?
systemctl is part of the systemd system and is used to:
Start services
Stop services
Restart services
Check service status
1.1 Check service status
Use the command:
systemctl status <service_name>
Examples:
systemctl status httpd
systemctl status apache2
systemctl status mariadb
systemctl status sshd
active (running) — service is running
inactive — service is stopped
failed — service has encountered an error
1.2 Start a service
Use the command:
systemctl start <service_name>
Examples:
systemctl start apache2
systemctl start mariadb
systemctl start sshd
1.3 Stop a service
Use the command:
systemctl stop <service_name>
Examples:
systemctl stop apache2
systemctl stop mariadb
systemctl stop httpd
1.4 Restart a service
Use the command:
systemctl restart <service_name>
Examples:
systemctl restart apache2
systemctl restart mariadb
systemctl restart sshd
The restart command is commonly used after making configuration changes.
1.5 Reload configuration only
Use the command:
systemctl reload <service_name>
Examples:
systemctl reload apache2
systemctl reload mariadb
1.6 Enable automatic startup
Enable a service to start automatically when the server boots:
systemctl enable <service_name>
Disable automatic startup:
systemctl disable apache2
1.7 List services
Use the command:
systemctl list-units --type=service
Output example:
UNIT LOAD ACTIVE SUB DESCRIPTION
httpd.service loaded active running The Apache HTTP Server
mariadb.service loaded active running MariaDB database server
memcached.service loaded active running Memcached
pure-ftpd.service loaded active running Pure-FTPd FTP server
sshd.service loaded active running OpenSSH server daemon
2. What is journalctl?
journalctl is used to view:
System logs
Service errors
Boot information
2.1 View all logs
Use the command:
journalctl
This may display a very large amount of log data.
2.2 Follow logs in real time
Use the command:
journalctl -f
It is similar to
tail -f
2.3 View logs for a specific service
Use the command:
journalctl -u httpd
Examples:
journalctl -u httpd
journalctl -u apache2
journalctl -u mariadb
2.4 View recent log entries
Use the command:
journalctl -u nginx -n 50
Shows the last 50 log entries.
2.5 View error logs only
Use the command:
journalctl -p err -b
2.6 View logs since last boot
Use the command:
journalctl -b
2.7 Filter logs by time
Show logs since a specific date:
journalctl --since "2026-01-01"
Show logs from the last hour:
journalctl --since "1 hour ago"
3. Troubleshooting examples
3.1 If a service is not running
Check its status:
systemctl status mariadb
If you see failure, inspect recent logs:
journalctl -u mariadb -n 50
3.2 Apache does not start
Check status:
systemctl status httpd
View detailed logs:
journalctl -xeu httpd
3.3 After configuration changes
Restart the service:
systemctl restart nginx
If an error occurs, check detailed logs:
journalctl -xeu nginx