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Check Linux Service Status: systemctl and service

2026-11-05 Sysadmin

Verified: tested on WSL2 Ubuntu 24.04 — systemctl status, is-active/is-enabled, service –status-all, and journalctl all passed.

1. TL;DR: pick by scenario

  • Interactive single service: systemctl status <service>, includes process, memory, recent logs.
  • Script checks for running/enabled: systemctl is-active / is-enabled, check exit codes.
  • Batch view of all services: systemctl list-units --type=service or list-unit-files.
  • Legacy SysV scripts: service --status-all, output [ + ]/[ - ].
  • Process and logs: pgrep/ps to locate PIDs, journalctl -u for logs.

2. systemctl status: preferred, with logs

systemctl status cron --no-pager
systemctl status cron --no-pager -l
systemctl status cron --no-pager --lines=20

Sample output:

● cron.service - Regular background program processing daemon
     Loaded: loaded (.../cron.service; enabled; preset: enabled)
     Active: active (running) since Thu 2026-11-05 00:44:16 CST
       Docs: man:cron(8)
   Main PID: 159 (cron)
      Tasks: 1
     Memory: 492.0K

systemctl status reads runtime state from systemd and includes recent journal logs [1]. By default it shows 10 lines and truncates long lines; --full disables truncation, --lines=N sets line count, -l equals --full. The .service suffix can be omitted; systemd completes it.

3. is-active / is-enabled: scripts and checks

systemctl is-active cron; echo "exit=$?"
systemctl is-enabled cron; echo "exit=$?"
systemctl is-failed cron; echo "exit=$?"
  • is-active: returns 0 if at least one unit is active, non-zero otherwise; prints the state word by default.
  • is-enabled: returns 0 if at least one unit file is enabled; output follows the man page table (enabled/enabled-runtime/masked, etc.).
  • is-failed: checks failed state; pair with --quiet to take only the exit code.

Use --quiet in scripts to avoid output noise:

if systemctl is-active --quiet cron; then echo "running"; fi

All three support glob patterns to match multiple units [1].

4. list-units / list-unit-files: batch view

systemctl list-units --type=service --state=running --no-pager --no-legend
systemctl list-units --type=service --state=failed --no-pager
systemctl list-unit-files --type=service --no-pager | grep -i cron
  • list-units: runtime state of loaded units; add --all to show inactive.
  • list-unit-files: installed unit files and their enablement (enabled/disabled/static/masked).

Both support --type= and --state= filters; list-units shows only active by default, add --all for everything [1].

5. service, ps, pgrep, journalctl: compatibility and process logs

service --status-all
service cron status
pgrep -a cron
ps -o pid,comm,args -C cron
journalctl -u cron --no-pager -n 10
  • service --status-all: runs status on every init script in alphabetical order; [ + ] running, [ - ] stopped, [ ? ] no status command; only effective for SysV tasks [2].
  • service <name> status: for a systemd unit it delegates to the equivalent systemctl command.
  • pgrep -a / ps -C: locate PIDs by process name, independent of systemd.
  • journalctl -u <service>: logs for that unit, supports --since/--until time filters [3].

6. Rollback, troubleshooting, limitations

Troubleshooting quick reference

Symptom Cause Fix
Unit xxx.service could not be found. not installed or name typo systemctl list-unit-files | grep to confirm name
status shows inactive (dead) service not started or exited systemctl start, then status
is-enabled outputs masked unit masked systemctl unmask
service --status-all no output or error pure systemd environment, no SysV scripts use systemctl list-units
journalctl cannot read system logs non-root, not in adm/systemd-journal group join the group or use sudo
process exists but systemctl does not know it service not registered as a unit locate with ps/pgrep, or add a unit file

Limitations

  • On WSL2, systemd needs systemd=true in /etc/wsl.conf; enabled in this environment.
  • service --status-all covers only SysV tasks; native systemd services are not listed.
  • Containers often have no systemd; systemctl errors out — use ps/pgrep or PID files instead.
  • is-failed prints a state word on some versions rather than staying quiet; always add --quiet in scripts.

Test record

  • Environment: WSL2 Ubuntu 24.04.4 LTS, kernel 6.6.114.1-microsoft-standard-WSL2, systemd running.
  • systemctl status cron: active (running), Main PID 159, memory 492K.
  • is-active/is-enabled: both returned 0, output active/enabled.
  • service --status-all: cron shown as [ + ].
  • list-unit-files: cron.service is enabled.
  • pgrep -a cron: PID 159, command line /usr/sbin/cron -f -P.
  • journalctl -u cron -n 5: printed startup logs normally.

References

Main commands above were tested on WSL Ubuntu (24.04) and checked against Debian-family and general distribution docs.

标签: linux sysadmin systemd

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