How to replace ^M with a new line in perl

Question

My test file has "n" number of lines and between each line there is a ^M, which in turn makes it one big string. The code I am working with opens said file and should parse out a header and then the subsequent rows, then searches for the Directory Path and File name. But because the file just ends up as a big string it doesn't work correctly

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

open  (DATA, "<file.txt") or die ("Unable to open file");

my $search_string = "Directory Path";
my $column_search = "Filename";
my $header =  <DATA>;
my @header_titles = split /\t/, $header;
my $extract_col = 0;
my $col_search = 0;

for my $header_line (@header_titles) {
  last if $header_line =~ m/$search_string/;
  $extract_col++;
}
for my $header_line (@header_titles) {
  last if $header_line =~m/$column_search/;
  $col_search++;
}

print "Extracting column $extract_col $search_string\n";

while ( my $row = <DATA> ) {
  last unless $row =~ /\S/;
  chomp $row;
  my @cells = split /\t/, $row;
 $cells[74]=~s/:/\//g;
$cells[$extract_col]= $cells[74] . $cells[$col_search];
print "$cells[$extract_col] \n";

}

When i open the test file in VI i have used

:%s/^M/\r/g

and that removes the ^M's but how do i do it inside this perl program? When i tried a test program and inserted that s\^M/\r/g and had it write to a different file it came up as a lot of Chinese characters.

Answer 1

If mac2unix isn't working for you, you can write your own mac2unix as a Perl one-liner:

perl -pi -e 'tr/\r/\n/' file.txt

That will likely fail if the size of the file is larger than virtual memory though, as it reads the whole file into memory.

For completeness, let's also have a dos2unix:

perl -pi -e 'tr/\r//d' file.txt

and a unix2dos:

perl -pi -e 's/\n/\r\n/g' file.txt