Functions like node_load() are not found

Question

I successfully installed Drush on Ubuntu 12.04, and I created a script containing the following line.

print_r(node_load(10));

I am calling the script with drush php-script --uri=http://localhost myscript.php which returns the following error.

PHP Fatal error: Call to undefined function node_load()

I also tried with drush --uri=http://localhost cache-get, but I get the following error.

Command cache-get needs a higher bootstrap level to run - you will need to invoke drush from a more functional Drupal environment to run this command.
The drush command 'cache-get' could not be executed.
Drush was not able to start (bootstrap) the Drupal database.
Hint: This may occur when Drush is trying to:

• bootstrap a site that has not been installed or does not have a configured database. In this case you can select another site with a working database setup by specifying the URI to use with the --uri parameter on the command line. See drush topic docs-aliases for details.
• connect the database through a socket. The socket file may be wrong or the php-cli may have no access to it in a jailed shell. See http://drupal.org/node/1428638 for details. Drush was attempting to connect to: Drupal version: 7.26
  Site URI: http://localhost
  Database driver: mysql
  Database hostname: 127.0.0.1
  Database username: username // This is shown correctly
  Database name: database_name // This is shown correctly
  PHP executable: /usr/bin/php
  PHP configuration: /etc/php5/cli/php.ini PHP OS: Linux
  Drush version: 7.0-dev
  Drush temp directory: /tmp
  Drush configuration:
  Drush alias files:
  Drupal root: /opt/lampp/htdocs
  Site path: sites/default

Answer 1

I finally figured out what was missing.

In my case I had to install the mysql-client-core-5.5 package with sudo apt-get install mysql-client-core-5.5.

Answer 2

I ran into the same problem (user_load() and other functions were not found), but had a different solution.

For me, it turned out that my sql privileges on the database were not correct.

I found the error by running my script with the -d option:

drush -d scr /path/to/my/script.php

I noticed in the log it spewed out that it was getting an error connecting to the database. I apparently had messed up the privs when I set them up. I sql granted the privs and my script ran just fine.

The error message about not being able to find a function was a total red herring.