You aren't aware of what the switches on your one-liner are doing for you. See perlrun

The -n is the most important one. It applies a while(<>) { ... } loop around your code. So, it is taking your input string, splitting it into lines, assigning each value in turn to $_, and then executing the body of your one-liner for each value. In a program, you have to specify that.

#!/usr/bin/perl

use strict;
use warnings;
use diagnostics;

my $A="abc\ndef\nghi\n";
my @list = split /\n/,$A;
while (<@list>) {
  ! /def/ and print
}

[download]

Updated: my most literal attempt didn't work, putting the split inside the while condition. So I use split to create an array. That works better.

Dum Spiro Spero

In reply to Re^3: Regex match on implicit default variable ($_) in a script, not a one liner by GotToBTru
in thread Regex match on implicit default variable ($_) in a script, not a one liner by Todd Chester

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