Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I have a program that for each run generates a new log file. To watch what's going on, I'd like to tail -f the log - only problem is that I don't actually know the file name in advance.

So, is there a way to follow all files that match a certain (shell glob) pattern? I guess I could easily script something like this, but I'm wondering if there's already a solution out there.

share|improve this question
Possible duplicate… – Peter Lundgren Nov 1 '12 at 12:40
up vote 4 down vote accepted

I don't think there's a direct way to do with with tail without knowing the name - if you knew that then tail --follow=name --retry would work and it would wait for the file to appear and then start following it.

I'd suggest writing a little shell script that uses inotifywait to watch for the file appearing and then starts tail -f to follow it.

share|improve this answer

If you don't know the file name in advance:

  1. decide on a filename, like foo.log
  2. watch that file: tail -F foo.log (doesn't matter if foo exists or not)
  3. use a tool to watch the directory for file changes and run a command

For the command, either:

  • move the new file to overwrite foo.log mv the_new_file_which_appeared foo.log (if the app logging opens once, this will work fine)
  • or just symlink: ln -s the_new_file_which_appeared foo.log - and tail should catch that.

To properly watch the directories (step 3), you need a configurable, clever tool.

Personally, I'd use Guard with the Guard::Process.

In practice, Guard is not much heavier than using shell scripts (it's a thin layer on top of inotify on Linux), and it's all very quick and easy to setup.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

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