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

use feature qw/ say /;
use strict;
use warnings;
while(  ) {
    chomp;
    my @elements = split /:/;
    my $interject = shift @elements;
    local $" = $interject;
    say $interject, "@elements";
}

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

Or on the linux shell command line:

perl -aF/:/ -pe '$i=shift @F;$_=$i.join $i,@F;' infile.txt