my @user_files = <longfilename>;
unshift(@user_files, 'blank');

# skipping to the $ufile line
# Make sure $choice is numeric and 
# within the range in user_files
if ( ($choice =~ /^\d+$/) &&
     ($choice > 0) && 
     ($choice <= scalar(@user_files)) ) {
   file_mod($user_files[$choice], $mail_flag);
} else {
   # Error condition, choice outside of range
}