ExecReload

ExecReload is a directive used in systemd service unit files. It specifies the command that systemd should execute when a reload of the service is requested, typically via systemctl reload <service>. The purpose of this directive is to allow a running daemon to re-read and apply its configuration without stopping or fully restarting.

When a reload is performed, systemd runs the program defined by ExecReload in the [Service] section. The command is commonly provided as an absolute path and may reference the unit’s main process using variables such as $MAINPID. Typical usages include signaling the main process to reconfigure itself (for example, ExecReload=/bin/kill -HUP $MAINPID) or invoking the application’s own reload command (for example, ExecReload=/usr/sbin/nginx -s reload).

Notes and behavior: ExecReload does not implicitly restart the service; it should implement a non-destructive reload of configuration. If ExecReload is not defined in a unit file, systemd’s reload action may have no effect unless the service is designed to handle reloads via other mechanisms or signals. The exact behavior can vary based on the service and how it handles reload requests.

See also: systemd, systemctl, unit file, ExecStart, ExecStop, Restart.