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if (! @ARGV) {
  use open ':raw'; # implicit binmode on each open
...
                           # see perlopentut
}
# ... now go do all that sysread stuff.

my @files = (@ARGV)?@ARGV:qw(-);
NEXTFILE:
...
  # don't forget that an eof here may not be a "real" eof,
  # but a signal to go to the next file
}

@/=map{[/./g]}qw/.h_nJ Xapou cets krht ele_ r_ra/;
map{y/X_/\n /;print}map{pop@$_}@/for@/