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Service Troubleshooting: When Things Go Wrong

Services fail. They don't start. They crash. You need to fix them.

Here's the thing: Troubleshooting services is essential. Learn it. You'll use it constantly.

Check Service Status​

systemctl status service-name

What it shows:

  • Service state (active, failed, inactive)
  • Recent log entries
  • Process information
  • Error messages

My take: status is your first step. It shows what's wrong.

View Service Logs​

# Journal logs
journalctl -u service-name
journalctl -u service-name -n 50    # Last 50 lines
journalctl -u service-name -f        # Follow logs

# Recent errors
journalctl -u service-name -p err

My take: Logs tell you why services fail. Read them.

Common Issues​

Service Won't Start​

# Check status
systemctl status service-name

# Check logs
journalctl -u service-name -n 100

# Check configuration
systemctl cat service-name

My take: Check status. Check logs. Check configuration. Find the problem.

Service Crashes​

# Check restart count
systemctl status service-name | grep "Main PID"

# Check logs for errors
journalctl -u service-name -p err

# Check if it's restarting
systemctl status service-name

My take: Crashes show in logs. Find the error. Fix it.

Service Fails to Enable​

# Check if service file exists
systemctl cat service-name

# Check syntax
systemctl daemon-reload
systemctl status service-name

My take: Enable failures are usually syntax errors. Check the service file.

Debugging Steps​

1. Check Status​

systemctl status service-name

2. Check Logs​

journalctl -u service-name -n 100

3. Test Manually​

# Run command manually
sudo -u service-user /path/to/command

My take: Run manually. See if it works. If it does, it's a service config issue.

4. Check Permissions​

# Check file permissions
ls -la /path/to/service/file

# Check user
id service-user

My take: Permissions matter. Check them.

5. Check Dependencies​

# Check what service needs
systemctl list-dependencies service-name

My take: Services need dependencies. Make sure they're running.

Common Mistakes (I've Made These)​

  1. Not checking logs: Logs tell you everything. Check them first.

  2. Not testing manually: Test commands manually. See if they work.

  3. Wrong user/permissions: Services need correct user and permissions.

  4. Missing dependencies: Services need dependencies. Make sure they're available.

  5. Not reloading systemd: After changing service files, reload systemd.

Real-World Examples​

Debug Failed Service​

# Check status
systemctl status myservice

# Check logs
journalctl -u myservice -n 100

# Test manually
sudo -u service-user /usr/local/bin/myservice

# Fix and restart
sudo systemctl restart myservice

Check Service Configuration​

# View service file
systemctl cat myservice

# Check if enabled
systemctl is-enabled myservice

# Check dependencies
systemctl list-dependencies myservice

What's Next?​

Now that you can troubleshoot services, you can fix problems. Or review System Services to understand services better.

Personal note: When services fail, I used to panic. Then I learned troubleshooting. Now I check status. Check logs. Fix the problem. It's systematic. Learn it.