This bash script adds a new administrator user to WordPress' MySQL database.

add-wp-admin.sh

#!/usr/bin/env bash

# This bash script adds a new administrator user to WordPress' MySQL database.

echo -n "Give a new admin user login name: "
read userlogin

echo -n "Email address for the user $userlogin: "
read useremail

# Ask for the password two times and check that they match
while true; do
    read -s -p "Give password for $userlogin: " userpw
    echo ""
    read -s -p "Write the password again: " userpw2

    if [ "$userpw" == "$userpw2" ]; then
      echo ""
      echo "Passwords match."
      break
    fi

    echo ""
    echo "Passwords do not match! Give the password again."
done

echo "Inserting new administrator user $userlogin to WordPress database."

echo -n "Give WordPress database name: "
read wpdatabase
echo -n "Give WordPress database's username: "
read wpdatabaseuser

# Insert new admin user to MySQL database and store output to a variable
mysql_output="$(echo "INSERT INTO \`wp_users\` (\`user_login\`, \`user_pass\`, \`user_nicename\`, \`user_email\`, \`user_status\`, \`user_registered\`, \`display_name\`) VALUES ('$userlogin', MD5('$userpw'), '$userlogin', '$useremail', '0', now(), '$userlogin');
INSERT INTO \`wp_usermeta\` (\`umeta_id\`, \`user_id\`, \`meta_key\`, \`meta_value\`) VALUES (NULL, (Select max(id) FROM wp_users), 'wp_capabilities', 'a:1:{s:13:\"administrator\";s:1:\"1\";}');
INSERT INTO \`wp_usermeta\` (\`umeta_id\`, \`user_id\`, \`meta_key\`, \`meta_value\`) VALUES (NULL, (Select max(id) FROM wp_users), 'wp_user_level', '10');
INSERT INTO \`wp_usermeta\` (\`umeta_id\`, \`user_id\`, \`meta_key\`, \`meta_value\`) VALUES (NULL, (Select max(id) FROM wp_users), 'nickname', '$userlogin');" | mysql -u$wpdatabaseuser -p $wpdatabase 2>&1 > /dev/null)"

# There should not be any output. So if there's output there probably was an error.
if [ -n "$mysql_output" ]; then
    echo $mysql_output
else
    echo "Creation ready. Try to login with the new user account."
fi