#!/usr/bin/perl # Compute all the new file names foreach $file (@ARGV) { print "Skipping non-.pnm file $file...\n" and next unless $file =~ /\.pnm$/; # Keep every fourth image $file =~ /\.(\d+)\.\w+$/; next unless $1 % 4 == 0; $newfile = $file; $newfile =~ s/\.pnm$/.bmp/; # Skip if new file exists print "$newfile already exists. Skipping...\n" and next if -e $newfile; # Make the bmp system "convert pnm:$file bmp:$newfile"; push @newfiles, $newfile; }