CODEWITHSUNDEEP
perl
Red Cricket
Red Cricket

Reputation: 10470

Why does my getpwent() call return the wrong user?

I always forget how to do this in Perl. Here's my script:

#!/usr/local/bin/perl -w
use strict;
use Data::Dumper;

my @got = getpwent();
my $username    = ${[getpwent()]}[0];

print Dumper( @got );
print "username is [$username]\n";

... and here is the output it produces ...

$VAR1 = 'root';
$VAR2 = 'xxxxxxxxxxxxxxxxxx';
$VAR3 = 0; 
$VAR4 = 0;
$VAR5 = ''; 
$VAR6 = '';
$VAR7 = 'myhost root';
$VAR8 = '/root';
$VAR9 = '/bin/bash';
username is [bin]

... and my question is, why is username equal 'bin' instead of 'root'?

Upvotes: 3

Views: 613

Answers (2)

mob
mob

Reputation: 118605

Repeated calls to getpwent return different rows in your password file (or whatever source of user information getpwent is using).

root is the first user listed in your password file, bin is the second.

Call endpwent to reset the iterator and replicate your previous calls to getpwent:

for (0..2) {
    print scalar getpwent(), "\n";
}
print "-- reset --\n";
endpwent();
for (0..3) {
    print scalar getpwent(), "\n";
}

outputs (YMMV)

SYSTEM
LocalService
NetworkService
-- reset --
SYSTEM
LocalService
NetworkService
Administrators

Upvotes: 3

Jim Davis
Jim Davis

Reputation: 5290

It iterates over users; you're calling it twice, and getting information for two users.

$ perl -E 'say $foo while $foo = getpwent()'
root
daemon
bin
sys
sync
...

Upvotes: 5

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