Apache cheatsheet

Service control

Command	Description
`systemctl status apache2`	Service status (Debian/Ubuntu)
`systemctl status httpd`	Service status (RHEL/CentOS)
`systemctl reload apache2`	Reload config without dropping connections
`apache2ctl configtest`	Test config syntax (Debian)
`httpd -t`	Test config syntax (RHEL)

Sites and modules (Debian/Ubuntu)

Command	Description
`a2ensite mysite.conf`	Enable a site
`a2dissite 000-default.conf`	Disable a site
`a2enmod proxy proxy_http ssl`	Enable modules
`a2dismod mpm_prefork`	Disable a module
`apache2ctl -S`	List vhosts and match order
`apache2ctl -M`	List loaded modules

Logs and debugging

Command	Description
`tail -f /var/log/apache2/error.log`	Follow error log (Debian)
`tail -f /var/log/httpd/error_log`	Follow error log (RHEL)
`tail -f /var/log/apache2/access.log`	Follow access log
`journalctl -u apache2 -f`	systemd journal for Apache
`ss -tlnp \| grep -E ':80\|:443'`	Check listeners
`curl -vI http://localhost/`	Test HTTP response headers

Minimal virtual host example

<VirtualHost *:80>
    ServerName www.example.com
    DocumentRoot /var/www/example
    ErrorLog ${APACHE_LOG_DIR}/example-error.log
    CustomLog ${APACHE_LOG_DIR}/example-access.log combined

    <Directory /var/www/example>
        Require all granted
    </Directory>
</VirtualHost>

Reverse proxy snippet

<VirtualHost *:80>
    ServerName api.example.com
    ProxyPreserveHost On
    ProxyPass / http://127.0.0.1:8000/
    ProxyPassReverse / http://127.0.0.1:8000/
</VirtualHost>

Pro tips

Always run configtest before reload — a bad config can prevent startup
Use apache2ctl -S to see which vhost handles a given name
Check error_log first — Apache logs module and permission errors there
Disable the default site on Debian if it steals traffic from your vhosts

Practice scenarios

Hands-on Apache scenarios on live Linux VMs: apache