Perl - while (<>) file handling [duplicate]

Answer 1

The name of the current file for <> is contained in special $ARGV variable.

You can cross-match your list of files from @ARGV parameter array with current file name to get the file's position in the list. Assuming the only parameters you expect are filenames, you can simply do:

my %filename_positions = map { ( $ARGV[$_] => $_ ) } 0..$#ARGV;

while (<>) {
    my $file_number = $filename_positions{$ARGV};
    #... if ($file_number == 0) { #first file     
}