Script for generating WP secret keys (like https://api.wordpress.org/secret-key/1.1/salt/, but suitable to use in .env file)

salts.php

<?php

function generate_salt($length) {
  $seed = 'abcdefghijklmnopqrstuvwxyz'
         .'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
         .'0123456789!@#$%^&*()"'; // and any other characters
  $rand = substr(str_shuffle(str_repeat($seed, $length)), 0, $length);
  return $rand;
}

function escape_value($val) {
  return '"' . preg_replace('/"|\\|\\$/', '\\\\$0', $val) . '"';
}

function generate_all() {
  $keys = ['AUTH_KEY',
    'SECURE_AUTH_KEY',
    'LOGGED_IN_KEY',
    'NONCE_KEY',
    'AUTH_SALT',
    'SECURE_AUTH_SALT',
    'LOGGED_IN_SALT',
    'NONCE_SALT'];
  $salts = [];
  foreach($keys as $k) {
    $salts[$k] = generate_salt(64);
  }
  return $salts;
}

function print_all($salts) {
  foreach($salts as $name => $val) {
    echo $name . '=' . escape_value($val) . "\n";
  }
}

print_all(generate_all());