"^M" is a carriage return character.    You can represent it in a regular expression as /\cM/ or /\x0D/ or /\015/ or /\r/.

local $/ = "\r\n";
chomp $string;
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or even use the ":crlf" PerlIO layer to automatically translate \r\n <—> \n.

On Windows, the layer is active by default, which is why the "^M problem" does not occur. But there's nothing that would keep you from using it on Unix, too, in case you need to handle Windows-style files.

See also flip, dos2unix, etc.

See also Caret Notation.

I recently ran into this same issue. I wrote the following short script to fix it. I don't know if it will work with everything, but it has for everything I have given it. Just supply the info it asks for, and it will create the FIXED file for you.

#!/usr/bin/perl -w
use strict;
use warnings;

my $FILE;
my $DST;
my $filename;
print("What file do you want to remove the trailing Carrige Returns fr
+om:");
while($filename=<STDIN>){
    chomp($filename);
    last;
}
open (FILE, '<', $filename) or die "Failed to open file:$!";
open (DST, '>', "FIXED".$filename) or die "Failed to open fix file:$!"
+;
while (<FILE>){
    if($_ =~ /\r$/){
        s/\r//;    
        print DST $_;    
    }
    else{
               print DST $_;
    }
}
print("The file $filename has been fixed. The new file name is FIXED".
+$filename.".\n");
close FILE;
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I am sure there are improvements that could be made, but it was a nice study on input output and basic regex.

I found that the ^M is indeed the same as a \r as is mentioned a couple of times above. This script just replaces it with nothing, essentially deleting it.

You may have an intention error in your while(<FILE>) loop. Right now, you're testing if the string ends with a \r and then you're removing the first occurrence of it. If your string is "Hello \rthere\r\n", your code would print "Hello there\r\n" to DST.

If I understand your intention correctly, I would replace the while loop with the following:

while (<FILE>){
    s/\r$//;
    print DST $_;
}
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If you want to get rid of all occurrences of \r in the line, you could just say:

while (<FILE>){
    s/\r//g;
    print DST $_;
}
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Heh, now that I look at it there, I notice that I neglected to close DST too. Oops.

Warning to future readers: Sorry; ^M is a 0x0d or "carriage return" a line feed is 0x0a (as correctly stated by jwkrahn, well before I posted this).

AR's reference to the use of a return in "macintosh line endings" is at best flawed, as Apple adopted nix'ish LFs for its more recent OSen.

Apart from the name "line feed" which should have been "carriage return", you were pretty spot on.

So don't be so hard on yourself.