How to Manage systemd Services on Linux

systemd is the init system on every mainstream Linux distro since 2015 — Ubuntu, Debian, Fedora, RHEL/Rocky/Alma, openSUSE, Arch. Knowing the eight commands below covers 99 percent of daily ops.

Prerequisites

• A Linux box with systemd as PID 1.
• sudo for any service control.

Step 1: Confirm systemd is PID 1

ps -p 1 -o comm=
# systemd
systemctl --version | head -1

If you see something else (init, openrc-init) you are on a non-systemd box — see Alpine apk for the OpenRC variant.

Step 2: Status, start, stop, restart, reload

sudo systemctl status nginx                 # current state + recent log lines
sudo systemctl start  nginx                 # start (no-op if already running)
sudo systemctl stop   nginx                 # stop
sudo systemctl restart nginx                # stop + start
sudo systemctl reload  nginx                # SIGHUP, only if the unit supports it
sudo systemctl reload-or-restart nginx      # reload if possible, restart otherwise

reload vs restart matters for production: reload preserves in-flight connections; restart drops them.

Step 3: Enable, disable, mask

sudo systemctl enable  nginx                # start on boot
sudo systemctl enable --now nginx           # enable AND start right now
sudo systemctl disable nginx                # don't start on boot
sudo systemctl mask    nginx                # make impossible to start; sym-linked to /dev/null
sudo systemctl unmask  nginx

mask is what you reach for when a stubborn package keeps re-enabling something you do not want (Apache when you installed Nginx, for example).

Step 4: List and inspect

systemctl list-units --type=service                 # currently loaded
systemctl list-units --type=service --state=running
systemctl list-units --type=service --state=failed  # what's broken
systemctl list-unit-files --type=service            # all known units + state
systemctl is-active nginx                            # active / inactive / failed
systemctl is-enabled nginx                           # enabled / disabled
systemctl cat nginx                                  # show the unit file(s)
systemctl show nginx | head -30                      # all properties

Step 5: Logs — journalctl

sudo journalctl -u nginx -f                  # follow this unit's log live
sudo journalctl -u nginx --since '1 hour ago'
sudo journalctl -u nginx --since '2026-05-27' --until '2026-05-27 12:00'
sudo journalctl -p err -b                    # errors+ since last boot
sudo journalctl -p err --since today
sudo journalctl _PID=12345                   # all logs from a PID
sudo journalctl -k                           # kernel ring buffer

For long-term retention, set Storage=persistent in /etc/systemd/journald.conf and create /var/log/journal/.

Step 6: Write your own unit

/etc/systemd/system/skyline-api.service:

[Unit]
Description=SKYLINE API service
After=network-online.target postgresql.service
Wants=network-online.target

[Service]
Type=simple
User=skyline
Group=skyline
WorkingDirectory=/opt/skyline-api
EnvironmentFile=/etc/skyline-api.env
ExecStart=/opt/skyline-api/bin/api
ExecReload=/bin/kill -HUP $MAINPID
Restart=on-failure
RestartSec=5
TimeoutStopSec=30

# Hardening
NoNewPrivileges=true
ProtectSystem=strict
ProtectHome=true
PrivateTmp=true
ReadWritePaths=/var/log/skyline-api /var/lib/skyline-api
LimitNOFILE=65536

[Install]
WantedBy=multi-user.target

Apply:

sudo systemctl daemon-reload
sudo systemctl enable --now skyline-api
sudo systemctl status skyline-api
sudo journalctl -u skyline-api -f

daemon-reload is required after editing any unit file. Skipping it is the number-one "but I changed it!" mistake.

Step 7: Timers (the systemd cron)

/etc/systemd/system/backup.service:

[Unit]
Description=Nightly skyline backup

[Service]
Type=oneshot
ExecStart=/usr/local/bin/skyline-backup.sh

/etc/systemd/system/backup.timer:

[Unit]
Description=Run skyline backup nightly

[Timer]
OnCalendar=*-*-* 02:30:00
Persistent=true
RandomizedDelaySec=5min

[Install]
WantedBy=timers.target

sudo systemctl daemon-reload
sudo systemctl enable --now backup.timer
systemctl list-timers

Persistent=true reruns missed timers if the host was off when they should have fired — something cron cannot do.

Step 8: Drop-in overrides

To tweak a packaged unit without editing the original:

sudo systemctl edit nginx

That opens an editor for /etc/systemd/system/nginx.service.d/override.conf. Add only the lines you want to override:

[Service]
LimitNOFILE=65536
Restart=on-failure

sudo systemctl restart nginx
sudo systemctl show nginx | grep -E '(LimitNOFILE|Restart)='

Updates to the package no longer wipe your customisations.

Verify

systemctl --failed
systemctl list-units --type=service --state=running | head -20
journalctl -p err -b | tail -20
systemctl list-timers | head -10

Conclusion

status, start, stop, restart, reload, enable, disable, list-units plus journalctl -u UNIT -f — eight commands and you are operational on any modern Linux distro.

Next steps

• Pair this with Linux file permissions when units fail because of file ownership.
• Schedule routine work via cron on Debian or systemd timers (Step 7 above).
• Write shell helpers via Bash scripting fundamentals.