How to List and Diagnose Failed systemd Services with systemctl

Listing Failed systemd Units

The systemctl list-units --state failed command displays all units whose state is failed . The output columns are:

UNIT : unit name (e.g., httpd.service)

LOAD : whether the unit definition was loaded

ACTIVE : high‑level activation state

SUB : low‑level activation state, varies by unit type

DESCRIPTION : human‑readable description

[root@localhost ~]# systemctl list-units --state failed
  UNIT          LOAD   ACTIVE SUB    DESCRIPTION
● httpd.service loaded failed failed The Apache HTTP Server

LOAD   = Reflects whether the unit definition was properly loaded.
ACTIVE = The high‑level unit activation state.
SUB    = The low‑level unit activation state.

1 loaded units listed. Pass --all to see loaded but inactive units, too.
To show all installed unit files use 'systemctl list-unit-files'.

Checking a Specific Service with is-failed

The systemctl is-failed <unit> option returns failed if the service did not start, otherwise active:

[root@localhost ~]# systemctl is-failed httpd
failed
[root@localhost ~]# systemctl is-failed vsftpd
active

Viewing Detailed Failure Reason

Use systemctl status <unit> to see why a service failed. In the example, the Apache HTTP Server fails because of a syntax error in /etc/httpd/conf/httpd.conf on line 354:

May 26 09:22:05 localhost httpd[2958]: httpd: Syntax error on line 354 of /etc/httpd/conf/httpd.conf: ...

Inspecting Logs with journalctl

If systemctl status does not reveal the cause, journalctl can be used to view the full journal. Filtering for the word error helps locate relevant entries:

[root@localhost ~]# journalctl | grep 'error'
May 26 09:22:05 localhost httpd[2958]: httpd: Syntax error on line 354 of /etc/httpd/conf/httpd.conf: ...

To view logs for a single unit, use the -u option:

[root@localhost ~]# journalctl -u httpd.service
-- Logs begin at Sun 2020-05-24 06:52:52 CST, end at Tue 2020-05-26 09:48:03 CST.
... (log entries showing the same syntax error) ...

Summary

We learned how to list failed services, check individual service states, examine detailed failure reasons with systemctl status, and dig into the system journal using journalctl to troubleshoot startup problems on Linux.