I either write the test as:

    grep {!/^\./}
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if I want to ignore all file (and directories) that start with a dot (like ls without the -a or -A option), or write it as

    grep {$_ ne "." && $_ ne ".."}
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which is a lot clearer than /^\.\.?\z/. It's longer, but anyone immediately sees you are excluding two names, and two names only.