Does specifying -type option improve find performance in linux?

Question

As you know there is an option for find command which allows you to tell if you're looking for a 'file' or 'directory'. I was wondering if specifying that would improve find performance (speed)? like:

find / -type file -name foo.bar

is faster than

find / -name foo.bar

or it does not make any difference?

Answer 1

Yes, in some cases it does improve performance.

By default find applies logical AND to its tests but the latter test is not evaluated if the former is false. So if you add a super fast test which almost always fails at the very beginning then it can save many executions of following (say: slow) tests and in this case this additional test does improve performance.

Go to directory with many files and few symlinks. Compare

time find -exec test -L {} \; -print

to

time find -type l -exec test -L {} \; -print

This is artificial yet enlightening example. The two tests (-type l and -exec test -L {} \;) do the same job, the two find commands yield the same results. However -exec creates additional process and this is relatively slow. In my home directory the first command takes two minutes; the second command takes six seconds.

Answer 2

1. Your commands won’t even work, for two reasons:

   • The starting directory (or directories), if any, must always appear before the test(s), if any, so your commands would have to be

     find / -name foo.bar …
     

   • Generally you can’t say -type file; it should be -type f.

2. Why would you even suspect that adding an additional test would improve performance?

3. Theoretically, it could decrease performance, because you’re doing

   if (filename = "foo.bar"  AND  filetype = "f")
       print filename
   

   instead of

   if (filename = "foo.bar")
       print filename
   

   i.e., you’re giving it more work to do.  In reality, though, the difference will be negligible.  find already has to get the filetype information to see which entries are directories (and therefore need to be searched recursively).  Once it has that information, checking whether it is a plain file requires just a few CPU instructions, and is very fast.