In Perl, how to remove ^M from a file?

Question

I have a script that is appending new fields to an existing CSV, however ^M characters are appearing at the end of the old lines so the new fields end up on a n

Answer 1

This one liner replaces all the ^M characters:

dos2unix <file-name>

You can call this from inside Perl or directly on your Unix prompt.

Answer 2

To convert DOS style to UNIX style line endings:

for ($line in <FILEHANDLE>) {
   $line =~ s/\r\n$/\n/;
}

Or, to remove UNIX and/or DOS style line endings:

for ($line in <FILEHANDLE>) {
   $line =~ s/\r?\n$//;
}

Answer 3

I prefer a more general solution that will work with either DOS or Unix input. Assuming the input is from STDIN:

while (defined(my $ln = <>))
  {
    chomp($ln);
    chop($ln) if ($ln =~ m/\r$/);

    # filter and write
  }

Answer 4

Slightly unrelated, but to remove ^M from the command line using Perl, do this:

perl -p -i -e "s/\r\n/\n/g" file.name