/usr/bin/file exit status always 0

Question

I'm trying to use /usr/bin/file to detect file types in a program but also would like it to report if the file does not exist. However the command always returns exit status 0.

Besides grepping the output, is there a way to make /usr/bin/file exit non-zero on file not found? Or is there another command that has this behavior?

Answer 1

The man page for file on my fedora, which is similar to centOS says explicitly that filesystem errors are not considered as an error in the exit status.

However, it also mentions the -E flag which you can use:

On filesystem errors (file not found etc), instead of handling the error as regular output as POSIX mandates and keep going, issue an error message and exit.

Answer 2

As far as other commands, Ruby can figure out whether files exist:

File.exists?('filename.txt')

You can incorporate it like this:

if File.exists?(filename)
  # Use the `file` command
else
  # Handle file not existing
end

If you do this multiple times, you can clean things up a bit by moving it into a Ruby method that handles all that and returns what you want.