UTF BOM

# program to remove a leading UTF-8 BOM from a file
# works both STDIN -> STDOUT and on the spot (with filename as argument)

if ($#ARGV > 0) {
  print STDERR "Too many arguments!\n";
  exit;
  }

my @file;  # file content
my $lineno = 0;

my $filename = @ARGV[0];
if ($filename) {
  open( BOMFILE, $filename ) || die "Could not open source file for reading.";
  while (<BOMFILE>) {
    if ($lineno++ == 0) {
      if ( index( $_, '' ) == 0 ) {
        s/^\xEF\xBB\xBF//;
        print "BOM found and removed.\n";
        }
      else { print "No BOM found.\n"; }
      }
    push @file, $_ ;
    }
  close (BOMFILE) || die "Can't close source file after reading.";

  open (NOBOMFILE, ">$filename") || die "Could not open source file for writing.";
  foreach $line (@file) {
    print NOBOMFILE $line;
    }
  close (NOBOMFILE) || die "Can't close source file after writing.";
  }
else { # STDIN -> STDOUT
  while (<>) {
  if (!$lineno++) {
    s/^\xEF\xBB\xBF//;
    }
  push @file, $_ ;
  }

  foreach $line (@file) {
    print $line;
    }
  }