sed, replace globally a delimiter with the first part of the line

Question

Lets say I have the following lines:

1:a:b:c
2:d:e:f
3:a:b
4:a:b:c:d:e:f

how can I edit this with sed (or perl) in order to read:

1a1b1c
2d2e2f
         


        

Answer 1

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

while () {
    if ( s/^([^:]+)// ) {
        my $delim = $1;
        s/:/$delim/g;
    }
    print;
}

__DATA__
1:a:b:c
2:d:e:f
3:a:b
4:a:b:c:d:e:f