You should have a look at opendir and readdir. I frequently have code that looks like:

opendir DIRHANDLE, 'directory-name' or die "Can't opendir: $!";
my @plain_files = grep( !/^\./ && -f, readdir( DIRHANDLE ) );
closedir( DIRHANDLE );
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I find it really handy to use grep to pick out the things I want and go from there. If you want to recurse into sub directories and/or do other fancy stuff, have a look at File::Find.