Programming Perl, 4th Edition

getpwent

getpwent
setpwent
endpwent

These functions conceptually iterate through your /etc/passwd file, though this may involve the /etc/shadow file if you’re the superuser and are using shadow passwords; it may get a lot fancier than that if you’re using some database- or network-based login system. The return value in list context is:

#  0     1       2    3    4      5        6     7    8
($name,$passwd,$uid,$gid,$quota,$comment,$gcos,$dir,$shell) = getpwent();

Some machines may use the quota and comment fields for purposes other than their named purposes, but the remaining fields will always be the same. To set up a hash for translating login names to UIDs, say this:

while (($name, $passwd, $uid) = getpwent()) {
    $uid{$name} = $uid;
}

In scalar context, getpwent returns only the username. The User::pwent module supports a by-name interface to this function. See getpwent(3).