Some code I wrote to add, remove, and change user names and passwords in .htpasswd with PHP:

function adduser($user, $pass) {

    try {

        $htpasswd = '.htpasswd';

        //$hash = '{SHA}'.crypt($pass, base64_encode($pass));

        $hash = crypt_apr1_md5($pass); //APR1-MD5

        $contents = $user . ':' . $hash;

        $lines = explode(PHP_EOL, file_get_contents($htpasswd)); // get .htpasswd

        print('<h4>input:</h4><pre>'.print_r(implode(PHP_EOL, $lines),true).'</pre>');

        $exists = false;

        foreach($lines as $line){

            $existing_user = explode( ':', $line );

            if ($existing_user[0] == $user) { //checks if user exists

                $contents = str_replace($line, $contents, $lines); //changes password for user

                $contents = implode(PHP_EOL, $contents);

                $exists = true;

                if ($pass == '') { // removes user if password is empty

                    $contents = str_replace($line, '', $lines); //removes user

                    $contents = array_filter($contents); // cleans empty space in array

                    $contents = implode(PHP_EOL, $contents);

                    $exists = true;

                }

            }

        }


        if ($exists == false) {

            $contents = implode(PHP_EOL, $lines) . PHP_EOL . $contents;
        }

        file_put_contents($htpasswd, $contents);

        print('<h4>output:</h4><pre>'.print_r($contents,true).'</pre>');

    }catch(Exception $e) {

        echo '<h3>fail: </h3>' . $e->getMessage();
    
    }

}

if(isset($_GET['user'])){

    adduser($_GET['user'], $_GET['pass']);

    echo '<h3>success</h3>';

}else{

    $htpasswd = '.htpasswd';

    $lines = explode(PHP_EOL, file_get_contents($htpasswd)); // get .htpasswd

    print('<h4>.htpasswd:</h4><pre>'.print_r(implode(PHP_EOL, $lines),true).'</pre>');

    echo '<h3>no user set</h3>';
}

Would love to streamline it and clean it up.