Check if a user is root - php

Question

How can i verify if a user is root in a PHP script ? What is the command ?
I tried something like that :
exec("su -l login < `echo password`");
but the su command can not receive password...
Note that the machine is isolated from internet so I can run PHP as root if needed.
EDIT:
I don't want to know if the current user who run the script is root or not.
I have a list of users in my PHP script and I want to know for each login if he has root privileges.

Answer 1

How about posix_getuid()?
if (0 == posix_getuid()) {
echo "Running as root.";
} else {
echo "not root";
}

Answer 2

First, ask yourself what exactly defines a login "having root privileges". AFAICT there are 2 basic solutions.
The old-school way, where sysadmins create multiple accounts with uid 0, which I - and I'm certainly not alone in this - consider to be a nightmare. In this scenario you could check all users in your list using posix_getpwnam and see if their uid matches 0.
The following code snippet does just that, $privileged will contain the users with root privileges :
$logins = array('root', 'john', 'guest', 'foo');
$privileged = array();
foreach($logins as $login) {
$userInfo = posix_getpwnam($login);
if ($userInfo !== FALSE) {
if ($userInfo['uid'] == 0) {
$privileged[] = $login;
}
}
}
The other (and imho only sane) way to do this is to add all users with root/administrative privileges to a specific group (wheel or admin are already used in different Linux distributions, find out which one works for you). This scenario is even simpler, since you can use posix_getgrnam to fetch all members in a specific group.
The following code snippet will match an array of logins you provide, and see who's a member with specific privileges, again $privileged will contain the result (ie. the users in your list that are a member of the group you specified) :
$logins = array('root', 'john', 'guest', 'foo');
$privileged = array();
$groupInfo = posix_getgrnam('admins');
if ($groupInfo !== FALSE) {
$privileged = array_intersect($logins, $groupInfo['members']);
}

Answer 3

Try This .
<?php
if (posix_getuid() == 0){
echo "This is root !";
// add more for root
} else {
echo "This is non-root";
}
?>

Answer 4

If you really mean "is root", then you can just check for whoami, and see if it comes up 'root'
exec("whoami");
If it's a smart thing to do is a different question ;)

Answer 5

Rewritten after your comment
"I don't want to know if the user who
run the script is root or no. I have
to check in a PHP script for some
login/password if they are root or
not"
I now understood that you need to perform a root authentication in PHP.
I suggest to use pwauth instead of whoami/login, etc.
Here is an example on how to use it from PHP, while I believe there can be a simpler way of testing.

Answer 6

If you want to see if a certain system user (as opposed to a web-service user) has root priviliedges, you can use the posix_getpwnam() function:
<?php
$u = posix_getpwnam("username");
if ($u == FALSE) {
print "no-such-user";
} elseif ($u["uid"] == 0) {
print "root";
} else {
print "non-root";
};
?>
Keep in mind that this only checks the username. If you also need to check the password you actually have to try to authenticate with the system.