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Editorial Team
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Asked: 2026-05-21T13:50:39+00:00

use strict; use warnings; my $newPasswd = ‘abc123’; my @lines = ( pwd =

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use strict;
use warnings;

my $newPasswd = 'abc123';
my @lines = ( "pwd = abc", "pwd=abc", "password=def", "name= Mike" );

my %passwordMap = (
    'pwd(\\s*)=.*'      => 'pwd\\1= $newPasswd',
    'password(\\s*)=.*' => 'password\\1= $newPasswd',
);

print "@lines\n";

foreach my $line (@lines) {
    while ( my ( $key, $value ) = each(%passwordMap) ) {
        if ( $line =~ /$key/ ) {
            my $cmdStr = "\$line =~ s/$key/$value/";
            print "$cmdStr\n";
            eval($cmdStr);
            last;
        }
    }
}

print "@lines";

run it will give me the correct results:

pwd = abc pwd=abc password=def name= Mike
$line =~ s/pwd(\s*)=.*/pwd\1= $newPasswd/
\1 better written as $1 at (eval 2) line 1 (#1)
$line =~ s/password(\s*)=.*/password\1= $newPasswd/
\1 better written as $1 at (eval 3) line 1 (#1)
pwd = abc123 pwd=abc password= abc123 name= Mike

I don’t want to see the warnings, tried to use $1 instead of \1, but it does not work. What should I do? Thanks a lot.

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1 Answer

  1. Editorial Team

    \1 is a regex pattern that means “match what was captured by the first set of capturing parens.” It makes absolutely no sense to use that in a replacement expression. To get the string captured by the first set of capturing parens, use $1.

    $line =~ s/pwd(\s*)=.*/pwd\1= $newPasswd/

    should be

    $line =~ s/pwd(\s*)=.*/pwd$1= $newPasswd/

    so

    'pwd(\\s*)=.*'      => 'pwd\\1= $newPasswd',
'password(\\s*)=.*' => 'password\\1= $newPasswd',

    should be

    'pwd(\\s*)=.*'      => 'pwd$1= $newPasswd',
'password(\\s*)=.*' => 'password$1= $newPasswd',

    or better yet

    qr/((?:pwd|password)\s*=).*/ => '$1= $newPasswd',
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