AgentSkillsCN

systemd-service

创建并管理 systemd 服务，以将程序作为后台服务运行，并支持自动重启、日志记录及依赖关系管理。适用于创建持久运行的后台服务、守护进程，或那些应在系统重启后依然存活、并在出现故障时自动重启的进程。

SKILL.md
--- frontmatter
name: systemd-service
description: Create and manage systemd services for running programs as background services with auto-restart, logging, and dependency management. Use when creating persistent background services, daemons, or processes that should survive reboots and auto-restart on failure.
triggers: ["service", "daemon", "background", "systemd", "auto-start", "on boot", "persistent service"]
category: automation
execution: claude-code
allowed-tools: ["Bash(systemctl*)", "Read", "Write"]

Systemd Service Creator

Creates and manages systemd service units for background processes.

When to Use

  • •Run programs as background services
  • •Auto-restart services on failure
  • •Start services on boot
  • •Manage dependencies between services
  • •Replace legacy init scripts
  • •Run Docker containers as services

Service Unit Structure

Basic Service Template

ini
[Unit]
Description=My Service Description
After=network.target
Requires=some-other.service

[Service]
Type=simple
User=username
WorkingDirectory=/path/to/workdir
ExecStart=/path/to/command
Restart=always
RestartSec=10

[Install]
WantedBy=multi-user.target

Service Types

  • •simple: Default, process started is main process
  • •forking: Process forks and parent exits
  • •oneshot: Process expected to exit (use with timers)
  • •notify: Service sends notification when ready
  • •dbus: Service acquires D-Bus name

Implementation Steps

1. Create Service File

bash
sudo nano /etc/systemd/system/myservice.service

2. Write Service Configuration

ini
[Unit]
Description=My Custom Service
After=network.target

[Service]
Type=simple
User=myuser
ExecStart=/usr/bin/python3 /home/myuser/app.py
Restart=on-failure
RestartSec=5

[Install]
WantedBy=multi-user.target

3. Reload Systemd

bash
sudo systemctl daemon-reload

4. Enable and Start

bash
# Enable (start on boot)
sudo systemctl enable myservice.service

# Start now
sudo systemctl start myservice.service

# Do both at once
sudo systemctl enable --now myservice.service

5. Verify Status

bash
sudo systemctl status myservice.service

Common Service Patterns

Docker Compose Service

ini
[Unit]
Description=My Docker App
After=docker.service
Requires=docker.service

[Service]
Type=simple
User=myuser
WorkingDirectory=/home/myuser/app
ExecStart=/usr/bin/docker compose up
ExecStop=/usr/bin/docker compose down
Restart=always

[Install]
WantedBy=multi-user.target

Python Application

ini
[Unit]
Description=My Python App
After=network.target

[Service]
Type=simple
User=myuser
WorkingDirectory=/home/myuser/app
Environment="PYTHONUNBUFFERED=1"
ExecStart=/usr/bin/python3 app.py
Restart=always
RestartSec=10

[Install]
WantedBy=multi-user.target

Node.js Application

ini
[Unit]
Description=My Node App
After=network.target

[Service]
Type=simple
User=nodeuser
WorkingDirectory=/home/nodeuser/app
ExecStart=/usr/bin/node server.js
Restart=on-failure
RestartSec=5

[Install]
WantedBy=multi-user.target

Restart Policies

  • •no: Never restart
  • •always: Always restart (even on clean exit)
  • •on-failure: Restart only on error exit
  • •on-abnormal: Restart on signals, timeout, watchdog
  • •on-abort: Restart only on unhandled signal

Logging

bash
# View service logs
journalctl -u myservice.service

# Follow logs in real-time
journalctl -u myservice.service -f

# Show recent logs
journalctl -u myservice.service -n 50

# Show logs since boot
journalctl -u myservice.service -b

Service Management Commands

bash
# Start service
sudo systemctl start myservice

# Stop service
sudo systemctl stop myservice

# Restart service
sudo systemctl restart myservice

# Reload config without restart
sudo systemctl reload myservice

# Enable on boot
sudo systemctl enable myservice

# Disable on boot
sudo systemctl disable myservice

# Check status
sudo systemctl status myservice

# Is service active?
systemctl is-active myservice

# Is service enabled?
systemctl is-enabled myservice

Environment Variables

ini
[Service]
Environment="VAR1=value1"
Environment="VAR2=value2"
EnvironmentFile=/etc/myservice/env

Dependencies

ini
[Unit]
# Start after these services
After=network.target postgresql.service

# Require these services (stop if they fail)
Requires=postgresql.service

# Want these services (don't stop if they fail)
Wants=redis.service

# Don't start with these services
Conflicts=other.service

Security Options

ini
[Service]
# Run as specific user/group
User=myuser
Group=mygroup

# Restrict capabilities
CapabilityBoundingSet=CAP_NET_BIND_SERVICE

# Read-only root filesystem
ProtectSystem=strict

# Private /tmp
PrivateTmp=yes

# Deny write to /home, /root, /run
ProtectHome=yes

Troubleshooting

bash
# Check service status
systemctl status myservice

# View logs
journalctl -u myservice -n 100

# Verify unit file syntax
systemd-analyze verify /etc/systemd/system/myservice.service

# Show unit dependencies
systemctl list-dependencies myservice

# Reload daemon after editing
sudo systemctl daemon-reload

Best Practices

  • •Always use absolute paths
  • •Set WorkingDirectory explicitly
  • •Use appropriate User (not root if possible)
  • •Set Restart policy for reliability
  • •Use After= for dependencies
  • •Test service manually before enabling
  • •Use EnvironmentFile for secrets
  • •Check logs after starting

Removing Services

bash
# Stop and disable
sudo systemctl stop myservice
sudo systemctl disable myservice

# Remove unit file
sudo rm /etc/systemd/system/myservice.service

# Reload daemon
sudo systemctl daemon-reload

# Reset failed state if needed
sudo systemctl reset-failed

Related Skills

  • •systemd-timer: Scheduled tasks with systemd
  • •cron-manager: Alternative for simple scheduled tasks
  • •bash-automation: Create scripts to run as services