I created a systemd service on my Pi 4 that writes std output to a file using StandardOutput=file:/file/location/file.log. Is there a way to limit the file size of the log file to prevent it from taking up too much space?

  • I don't think there is in this constellation. What would you like to happen when the maximum size is reached? Service gets killed? New file gets started, and old file renamed, old-old files get deleted? Jan 10 at 16:23
  • @MarcusMüller Best case, I would like the oldest logs to be removed and the newest ones added to the log file. At the very minimum I would like the service to stop writing to that file.
    – SudoObey
    Jan 10 at 16:28
  • ah removing the beginning of a file is not something you can "easily" implement on a UNIXoid system (or in fact, any system I'm aware of), that would always require a complete re-writing of the file. What you could do is use logrotate! Jan 10 at 16:31
  • btw, almost certain you either want append: or truncate:, not file:. Jan 10 at 16:33

1 Answer 1


I think the most forward way of dealing with this is using the logrotate program (probably already installed, and automatically running periodically, e.g. once a day).

For that to work, you'd add a file yourservice.conf in the /etc/logrotate.d directory (check that /etc/logrotate.conf contains include /etc/logrotate.d). This makes a new file every (a little more than) 10 MB, and keeps the most recent 5:

   /file/location/file.log {
       rotate 5
       size 10M
           systemctl restart yourservice.service

If the frequency of logrotate.timer is too low (default: daily), i.e. if your program writes more than size in a single day, you will have to modify the timer interval.

Note that you would be well-advised to not even start writing high-rate logs you don't need on a raspberry pi, if /file/location/file.log is on an SD card: These tend to wear off relatively quickly. Worn-out flash storage is the nr 1 reason for data loss and hardware-caused failure in RPis and similar SBCs.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.