You're using (parenthesis) when you should be using {curly-braces}. The first argument to grep is a { BLOCK } that describes how you want to search the items in the following list. 
@existing_files = grep { -e $_ } @untested_files;

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This will return true for any item that can be said to "exist" in the file system. You may want to use -f to test if it's a file (versus, say, -d to see if it's a directory), etc. See _X for additional tests you can perform. Note also that $_ is implied, so you can leave that out: { -e }

# alternate syntax
@exiting = grep(-e, @untested);

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See the documentation for grep, which is what I would have done in the first place.

In reply to Re: Seeking multiple defined files by Fastolfe
in thread Seeking multiple defined files by DaWolf

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