linux / systemd

updated July 20, 2026

I run long-lived processes on Linux VMs as systemd services so they survive SSH logout and restart on crash or reboot. Read their output with linux / logs.

A service unit

A unit file describes how to start a process. This runs the farmer from cmd / cibot:

# /etc/systemd/system/cibot-farmer.service
[Unit]
Description=cibot farmer
After=network-online.target
Wants=network-online.target

[Service]
User=croaky
EnvironmentFile=/etc/cibot-farmer.env
ExecStart=/usr/local/bin/cibot farmer
Restart=always
RestartSec=2

[Install]
WantedBy=multi-user.target

Install and start it:

sudo cp cibot-farmer.service /etc/systemd/system/
sudo systemctl enable --now cibot-farmer

enable starts it on every boot and --now also starts it right away. Restart=always brings it back if it exits.

Template units

To run several copies of one process, use a template unit. The @ suffix and %i placeholder let a single file serve many instances:

# /etc/systemd/system/cibot-worker@.service
[Service]
User=croaky
EnvironmentFile=/etc/cibot.env
ExecStart=/usr/local/bin/cibot worker
Restart=always

sudo systemctl enable --now cibot-worker@{1..8}

That starts eight workers, cibot-worker@1 through @8, from one unit file.

Environment variables

systemd gives a process a minimal environment, so I keep config and secrets in an EnvironmentFile. The path /etc/cibot.env is my own choice; Debian and Ubuntu favor /etc/default/<name>, and Red Hat favors /etc/sysconfig/<name>.

# /etc/cibot.env
FARMER_URL=http://10.50.96.89:1994
BOX_TOKEN=...
PATH=/usr/local/go/bin:/usr/local/bin:/usr/bin:/bin

Two things worth knowing:

The default PATH is minimal, so set it explicitly when the process shells out to tools like go, git, or psql.
The file holds secrets, so restrict it with sudo chown root:root /etc/cibot.env && sudo chmod 600 /etc/cibot.env.

Everyday commands

sudo systemctl restart cibot-farmer
sudo systemctl stop cibot-farmer
systemctl is-active cibot-farmer
systemctl show cibot-farmer -p NRestarts --value

After editing a unit file, reload systemd's view before restarting:

sudo systemctl daemon-reload

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