It's possible to do something like that very easily with a one-liner. However, more verbose is probably what you're looking for if you intend to include this within a script.

my $file = '/home/bob/db.txt';
open my $fh, $file or die "$file: $!";

my $pass;

while (<$fh>) {
    chomp;
    my @fields = split /\s+/;
    if ($fields[0] eq 'user@example.com') {
        $pass = $fields[1];
        last;
    }
}
close $fh;
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