database=...
user=...
PASSWD=`cat password_file | grep $database | grep $user | cut -d: -f2`

##</code><code>##

my $database = '...';
my $user = '...';
my $PASSWD = '';
open(my $fh, '<', 'password_file') or die("open: $!\n");
while (<$fh>) {
   chomp;
   $PASSWD = (split /:/)[2] if /$database/ && /$user/;
}

##</code><code>##

PASSWD=`perl -e"chomp; print((split /:/)[2]) if /$database/ && /$user/" < password_file`

##</code><code>##

PASSWD=`perl -F: -lane'print $F[1] if $F[2] eq $ARGV[0] && $F[0] eq $ARGV[1]' $database $user < password_file`