Great answer. Thank you (and thank you to all who added their two cents). I solved this by using two loops. One to create the file list and the second to go through the list and issue the system commands for each item.

sub gzip {
    my $cmd = shift;
    my $dir = shift;
    my ($file, $fullfile);
    my @files = ();
    print "$cmd files in $dir...\n";

    # Make sure command is secure and predictable.
    if ( $cmd eq 'zip' ){
        $cmd = 'gzip';
    } elsif ( $cmd eq 'unzip' ){
        $cmd = 'gunzip';
    } else {
        warn "zip or unzip command not given $!";
    }

    # Generate list of files
    opendir DIR, $dir or warn "Cannot open $dir $!";
    while ( defined ( $file = readdir(DIR) ) ){

        $fullfile = "$dir/$file";
        next if ( !-f $fullfile
                || $file =~ m/\.txt$/
                || $file !~ m/^[\w-]+(\.[\w-]+)*$/ );

        push @files, $fullfile;
    }
    closedir DIR;

    # Using file list from above, issue zip or unzip command.  You can
+not do
    # both in the same loop as the readdir may pickup the newly create
+d files
    # and try to process them.  Thus you may endup to zipping a zipped
+ file or
    # unzipping an upzipped file.
    while (<@files>) {
        system ( "$cmd $_") == 0 or warn "Cannot $cmd $fullfile : $!";
    }
}

[download]

---

---

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

Outside of code tags, you may need to use entities for some characters:

	For:		Use:
	&		&
	<		&lt;
	>		&gt;
	[		&#91;
	]		&#93;

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.