http://www.perlmonks.org?node_id=932537


in reply to Modify a txt file

One way to do it: 

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

local $/ = "";   # paragraph mode

while (<DATA>) {
    my ($num) = /^(\d+)/;
    s/\w+/$num/g;
    print;
}

__DATA__
0       ASDF
        ASEE
        ASEE

13      DERG
        DREG

28      QWER
        QWER

42      WERT
        WERT
        WERT

55      QWEASD
        QWEASD
        QWEASD
        QWEASD

[download]

(note that $/ = "" is not the same as $/ = undef, see perlvar)

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