Linux Survival Basics
Read-onlyCheck Whether a Service Starts at Boot
A service is manually started during an incident, but nobody verifies whether systemd will start it after reboot.
Command
systemctl is-enabled nginxBefore you run this
System impact: Read-only. Low when scoped to the shown target.
When not to use it: Do not use it to check whether the service is currently running; use systemctl is-active for that.
Expected output
enabled
System impact
Read-only. Nothing changes. systemctl prints enabled, disabled, static, masked, or another enablement state.
Recovery / rollback: no state is changed.
When to use it
Use after installing services, recovering incidents, or manually starting daemons.
When not to use it
Do not use it to check whether the service is currently running; use systemctl is-active for that.
next steps
Related commands
Inspect One Service Without Pager Traps
Make systemctl status safe for scripts, screenshots, and quick incident notes.
systemctl status nginx --no-pager --lines=30
Show a Service LimitNOFILE
A shell ulimit is not the service limit.
systemctl show nginx -p LimitNOFILE --no-pager
Check If a Service Is Active
Get a clean yes-or-no service state without the full status page.
systemctl is-active nginx
Check apt Daily Timers
Automatic apt timers can explain locks that seem mysterious.
systemctl list-timers apt-daily* --no-pager
Read Current-Boot Logs for One Service
Ignore stale logs and inspect only what happened since this boot.
journalctl -u nginx -b --no-pager -n 80
Study mapping
Use this as independent command practice: read the notes, predict the output, then compare it with the example before using a real shell.
Independent study support only. No affiliation, endorsement, exam dumps, or real exam questions.