How can I pull a line out of /etc/passwd if its corresponding shadow entry is 999999?

Question

I want to compare each user in the passwd file with his entry in the shadow file, and print out the whole line of the passwd file if the entry in the shadow file matches 999999. What is the easiest way in Perl to do this? Or I suppose I could awk the values out of one file and match in the other file? What is the best way of doing this?

Answer 1

awk -F":" 'FNR==NR&&$5=="99999"{user[$1];next}($1 in user)' /etc/shadow /etc/passwd

change FNR==NR&&$5=="99999" to FNR==NR&&$5=="99999"&&$2!="!!" if you want to exclude lines with "!!"

Answer 2

#! /usr/bin/perl

use warnings;
use strict;

sub read_passwd {
  open my $fh, "<", "/etc/passwd" or die "$0: open: $!";

  my %passwd;
  while (<$fh>) {
    next unless /^([^:]+)/;
    $passwd{$1} = $_;
  }

  \%passwd;
}

my $passwd = read_passwd;

open my $fh, "<", "/etc/shadow" or die "$0: open: $!";
while (<$fh>) {
  my($user,$maxage) = (split /:/)[0,4];
  next unless $maxage eq 99999;
  if ($passwd->{$user}) {
    print $passwd->{$user};
  }
  else {
    warn "$0: no passwd entry for '$user'";
  }
}

Answer 3

sudo perl -F: -lane '(1..eof)?($_{$F[0]}=$_):/999999/&&($_=$_{$F[0]})&&print' /etc/passwd /etc/shadow

Answer 4

You could use AnyData::Format::Password:

#!/usr/bin/perl

use strict; use warnings;
use AnyData;

my $passwd = adTie(Passwd => 'passwd' );
my $shadow = adTie(Passwd => 'shadow' );

for my $user (keys %$shadow) {
    if ( $user->{fullname} and $user->{fullname} eq '999999' ) {
         print $passwd->{$user->{username}}{fullname}, "\n";
    }
}

Output:

...
Privilege-separated SSH
RPC Service User
Anonymous NFS User
HAL daemon

Or:

for my $user (keys %$shadow) {
    if ( $user->{fullname} and $user->{fullname} eq '999999' ) {
        my @values = map { defined $_ ? $_ : '' }
            @{ $passwd->{$user->{username}} }{@fields};
        print join(':', @values), "\n";
    }
}