Drush for Developers Second Edition (2015)
Chapter 1. Introduction, Installation, and Basic Usage
Drush is a command-line interface for Drupal. It can also serve as an alternative to write scripts using PHP instead of BASH. The Drush ecosystem is vast. Every year, at DrupalCon, the Drush core team gives an update on the bleeding edge features being developed by them and by contributors all over the world.
Tasks such as clearing caches, running database updates, executing batch scripts, and managing remote websites are just a glimpse of what you can do with Drush.
Here is an example. Imagine that you have pushed new code for your website and need to run database updates. Normally this would involve the following steps:
1. Back up your database.
2. Open your web browser and navigate to http://example.com/user.
3. Authenticate as administrator.
4. Navigate to http://example.com/update.php.
5. Run database updates and wait for a confirmation message.
Now, here is how you can accomplish the preceding steps with Drush:
$ drush @example.prod sql-dump > dump.sql
$ drush @example.prod updatedb --yes
That's it. We did not even have to open an SSH connection or a web browser. The first command created a database backup and the second one executed pending database updates. In both these commands, we used @example.prod, which is a Drush site alias used to load configuration details about a particular site. We will see Drush site aliases in detail in Chapter 5, Managing Local and Remote Environments.
Drush is highly customizable. You can adjust it to fit a specific workflow. This is especially helpful when working on a Drupal project within a team; you can define security policies, wrap commands with sensible defaults, sanitize a copy of the production database automatically, and so on. This is the area that this book will focus on. We will go through some common processes during a Drupal project and discover how we can automate or simplify them using Drush. Let's start!
This chapter is an introduction and will cover the following topics to get you up to speed:
· Installation requirements
· Drush command structure
· Understanding Drush's context system
Installation requirements
The following are the installation requirements for Drush. If you have already installed it, simply make sure that you are running version 7.0.0-alpha5 (https://github.com/drush-ops/drush/releases/tag/7.0.0-alpha5) or higher by executing drush --version in the command line, and skip forward to the next section of this chapter.
Operating system
Drush works on Unix-like operating systems (such as Ubuntu and OSX) and Windows operating systems.
If you use Windows, consider using something like VirtualBox (https://www.virtualbox.org) to install a virtual machine that runs, for example, Ubuntu (http://www.ubuntu.com). If you still want to use Drush on Windows, there is an installer available athttp://www.drush.org/drush_windows_installer. Note, however, that the installer installs an older version of Drush, so some of the contents of this book won't work.
PHP
Let's start by making sure that you have PHP 5.3.0 or greater installed. To do so, open a terminal and run the following command:
$ php -v
The output should look something like the following code screenshot:
As you can see, I am using PHP 5.5.9. If you get a Command not found message or your version is lower than 5.3.0, you will need to install or upgrade PHP. Refer to your vendor documentation to do this as the steps will vary.
Installing Composer
On Linux and OSX platforms, the recommended way to install Drush is through Composer (https://getcomposer.org), a dependency manager that has become the standard in the PHP world. Installing Composer can be accomplished with the following commands:
$ cd $HOME
$ curl -sS https://getcomposer.org/installer | php
$ sudo mv composer.phar /usr/local/bin/composer
If you find any issues while running the preceding commands or while installing it through a packaging system such as homebrew, then take a look at the official installation instructions for Composer (https://getcomposer.org/doc/00-intro.md#globally-on-osx-via-homebrew). Once you have completed the installation, you can verify that it works by running the following command:
$ composer about
Composer - Package Management for PHP
Composer is a dependency manager tracking local dependencies of your projects and libraries.
See http://getcomposer.org/ for more information.
Note
If you have already installed Composer, make sure that it is up to date by running composer self-update (https://getcomposer.org/doc/03-cli.md#self-update).
Drush installation on Linux and OSX
At the time of writing this book, the latest available version of Drush is 7.0.0-alpha5 (https://github.com/drush-ops/drush/releases/tag/7.0.0-alpha5). This is the version that we will use. The Drush core team does a fantastic job of keeping backwards compatibility between major versions, so if you have already installed a more recent version of Drush, you should be okay as practically all the examples in the book will work.
Let's go ahead and install Drush. Once Composer has been installed (see the previous section on installing Composer), you can install Drush with the following command:
$ composer global require drush/drush:7.0.0-alpha5 -v
Changed current directory to /home/juampy/.composer
./composer.json has been updated
Loading composer repositories with package information
Updating dependencies (including require-dev)
- Installing drush/drush (7.0.0-alpha5)
Downloading: 100%
Extracting archive
drush/drush suggests installing youngj/httpserver
Writing lock file
Generating autoload files
The preceding command has downloaded Drush 7.0.0-alpha5 into $HOME/.composer/vendor/bin/drush. In order to use Drush from anywhere in the system, we need to make sure that Composer's bin directory is present at our $PATH environment variable. We can do so with the following commands:
$ sed -i '1i export PATH="$HOME/.composer/vendor/bin:$PATH"' \
$HOME/.bashrc
$ source $HOME/.bashrc
Note the use of $HOME and $PATH, which are environment variables. $HOME contains the location of your home directory, while $PATH represents a list of directories to look for executable files. You can view the contents of these variables by executing echo $HOME or echo $PATH. Take a look at your home directory to check whether there is .bash_profile, .bash_login, or .profile file at $HOME. If you find them, adjust the preceding commands, so the $PATH variable is adjusted in these files as well.
Finally, we can test that Drush has been installed successfully and contains the right version:
$ cd $HOME
$ drush --version
Drush Version : 7.0.0-alpha5
Manual installation
If you prefer to install Drush manually, then follow these steps:
1. Start by opening a web browser, and download and uncompress the contents of Drush 7.0.0-alpha5 (https://github.com/drush-ops/drush/releases/tag/7.0.0-alpha5) into your home directory.
2. Open a terminal and move the drush directory into your system's shared directory:
3. $ sudo mv $HOME/drush /usr/share
4. Set proper permissions to the drush executable file:
5. $ sudo chmod u+x /usr/share/drush/drush
6. Create a symbolic link of the Drush executable to any of the directories listed at your $PATH environment variable so that you do not have to type /usr/share/drush/drush every time you use it.
7. $ echo $PATH
8. /home/juampy/.composer/vendor/bin:/usr/local/sbin:
9. /usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:
10. /usr/local/games
11.$ sudo ln -s /usr/share/drush/drush /usr/local/bin/drush
12. The next step consists of installing Composer dependencies for Drush:
13.$ cd /usr/share/drush
14.$ composer install
15.Loading composer repositories with package information
16.Installing dependencies (including require-dev) from lock file
17. - Installing d11wtq/boris (v1.0.8)
18. - Installing pear/console_table (1.1.5)
19. - Installing phpunit/php-token-stream (1.2.2)
20. - Installing symfony/yaml (v2.2.1)
21. - Installing sebastian/version (1.0.3)
22. - Installing sebastian/exporter (1.0.1)
23. - Installing sebastian/environment (1.0.0)
24. - Installing sebastian/diff (1.1.0)
25. - Installing sebastian/comparator (1.0.0)
26. - Installing phpunit/php-text-template (1.2.0)
27. - Installing phpunit/phpunit-mock-objects (2.1.5)
28. - Installing phpunit/php-timer (1.0.5)
29. - Installing phpunit/php-file-iterator (1.3.4)
30. - Installing phpunit/php-code-coverage (2.0.9)
31. - Installing phpunit/phpunit (4.1.3)
32. - Installing symfony/process (v2.4.5)
33. pear/console_table suggests installing pear/Console_Color (>=0.0.4)
34. phpunit/phpunit suggests installing phpunit/php-invoker (~1.1)
35.Generating autoload files
36. Finally, verify the installation:
37.$ cd $HOME
38.$ which drush
39. /usr/local/bin/drush
40.$ drush --version
41. Drush Version : 7.0.0-alpha5
The main README file at the Drush repository has a great section on POST-INSTALL tasks (https://github.com/drush-ops/drush#post-install) with additional information on configuring PHP and extra settings for environments such as MAMP. It's worth taking a look at it.
The Drush command structure
Drush offers a broad list of commands that cover practically all the aspects of a Drupal project. If you are already fluent with executing commands in the terminal, you can skip this section. Otherwise, keep on reading to discover what arguments and options are and how these affect the behavior of a command.
We can view the available list of commands by running drush help. Additionally, running drush help some-command will show you detailed information about a particular command.
Executing a command
Let's start with a very simple command such as core-status, which prints environment information about Drush and, if available, a Drupal site. Assuming that we have a Drupal project installed at /home/juampy/projects/drupal, let's run this command here and see its output:
$ drush core-status
Drupal version : 7.29-dev
Site URI : http://default
Database driver : mysql
Database username : root
Database name : drupal7x
Database : Connected
Drupal bootstrap : Successful
Drupal user :
Default theme : bartik
Administration theme : seven
PHP executable : /usr/bin/php
PHP configuration : /etc/php5/cli/php.ini
PHP OS : Linux
Drush version : 7.0.0-alpha5
Drush temp directory : /tmp
Drush alias files :
Drupal root : /home/juampy/projects/drupal
Site path : sites/default
File directory path : sites/default/files
Temporary file directory path : /tmp
The preceding output informs us about the main configuration of the Drupal project plus some Drush environment settings.
Providing arguments to a command
The core-status command accepts a single argument that specifies which setting is to be retrieved (you can see this information by running drush help core-status). An argument is a string of text that acts as an input data for a command. Arguments are entered after the command name and are separated by spaces. Therefore, if we need to print just the items containing version in the setting name, we can execute the following command:
$ drush core-status version
Drupal version : 7.29-dev
Drush version : 7.0.0-alpha5
Drush commands might accept zero to any number of arguments depending on their nature. Beware that some commands expect arguments to be given in a certain order. For example, the variable-set command, used to change Drupal environment variables, requires the first argument to be the variable name and the second argument to be the variable's new value. Hence, the following example sets the site-name variable to the My awesome site value:
$ drush variable-set site-name "My awesome site"
site-name was set to "My awesome site". [success]
Altering a command's behavior through options
Drush commands might accept options through the command line, which alter their default behavior. Options are in the form of --option-name or --option-name=value. Additionally, some options have a shorter version. For example, you can accept all confirmations for a Drush command by appending --yes or its shorter version: -y.
Let's take a look at options with an example. The core-status command has an option to show the database password. We will now add it to the command and inspect the output:
$ cd /home/juampy/projects/drupal
$ drush core-status --show-passwords database
Database driver : mysql
Database username : root
Database password : mysecretpw
Database name : drupal7x
Database : Connected
The --show-passwords option orders the core-status command that we want to see the database password of the Drupal site being bootstrapped.
Structuring command invocations
Excluding some exceptions, there is no strict ordering for options and arguments when you run a command. Besides, Drush does a great job parsing arguments and options no matter how we mix them up in the input. However, our commands will be more readable if we follow this pattern:
$ drush [global options] [command name] [command options] [arguments]
Here is an example:
$ drush --verbose core-status --show-passwords database
And the following are the commands used in the previous example:
· --verbose: This is a Drush global option. You can see all the available global options by running drush topic core-global-options.
· core-status: This is the command that we are running.
· --show-passwords: This is an option of the core-status command.
· database: This is an argument for the core-status command.
Besides the fact of higher clarity by using the preceding structure, there are some commands in Drush that require options to be given in this order. This is the case of the core-sync Drush command, which is a wrapper of the actual Unix rsync command used to copy files and directories. Let's take a look at the following example:
$ drush rsync @self:%files/ /tmp/files --dry-run
You will destroy data from /tmp/files and replace with data from /home/juampy/projects/drupal/sites/default/files/
Do you really want to continue? (y/n):
The preceding command copies files recursively from a Drupal project into /tmp/files. The --dry-run option is an rsync specific option that attempts to copy files but does not make any actual changes. Now, let's try to run the same command but this time placing the option before the command name:
$ drush --dry-run rsync @self:%files/ /tmp/files
Unknown option: --dry-run. See `drush help core-rsync` for available options. To suppress this error, add the option –strict=0. [error]
We can see in the preceding output that Drush attempted to evaluate the --dry-run option and failed as it did not recognize it. This example demonstrates that you should carefully read the description of a command by running drush help command-name in order to understand its options, arguments, and ordering.
Command aliases
Most of Drush commands support a shorter name to be used when invoking them. You can find them in parenthesis next to each command name when running drush help, or in the Aliases section when viewing the full help of a command.
For example, the core-status command can also be executed with status or just st, which means that the following commands will return identical results:
$ drush core-status
$ drush status
$ drush st
Note
For clarity, we will not use command aliases in this book, but these help us to work faster. So, it is worthwhile to use them.
Understanding Drush's context system
Drush is decoupled from Drupal. This means that it does not necessarily need a Drupal site to work with. Some commands do require a Drupal project to bootstrap, while for others, this might be optional. Let's take core-status as an example. This command gives us information about the current context. If we run this command outside of a Drupal project, we will obtain configuration details for Drush and our local environment:
$ cd $HOME
$ drush core-status
PHP executable : /usr/bin/php
PHP configuration : /etc/php5/cli/php.ini
PHP OS : Linux
Drush version : 7.0.0-alpha5
Drush temp directory : /tmp
Drush alias files :
Now, if we change directory to a Drupal project, we will get extra information about it:
$ cd /home/juampy/projects/drupal
$ drush core-status
Drupal version : 7.29-dev
Site URI : http://default
Database driver : mysql
Database username : root
Database name : drupal7x
Database : Connected
Drupal bootstrap : Successful
Drupal user :
Default theme : bartik
Administration theme : seven
PHP executable : /usr/bin/php
PHP configuration : /etc/php5/cli/php.ini
PHP OS : Linux
Drush version : 7.0.0-alpha5
Drush temp directory : /tmp
Drush alias files :
Drupal root : /home/juampy/projects/drupal
Site path : sites/default
File directory path : sites/default/files
Temporary file directory path : /tmp
In the preceding scenario, Drush finds out that it is currently at the root of a Drupal project that uses the default location to store its settings (sites/default). Therefore, it is able to bootstrap Drupal and load its configuration.
Setting the context manually
We do not have to be at the root of a Drupal project in order to run Drush commands against it. Instead, we can append additional options that will let Drush find it. For example, we could run the core-status command from a different directory, adding the --rootoption that points to the root of our Drupal project:
$ cd /home/juampy
$ drush --root=/home/juampy/projects/drupal core-status
Drupal version : 7.29-dev
Site URI : http://default
Database driver : mysql
Database username : root
Database name : drupal7x
Database : Connected
Drupal bootstrap : Successful
Drupal root : /home/juampy/projects/drupal
Site path : sites/default
As we can see at the command output, Drush did bootstrap Drupal although we were not at its root directory. On a multisite Drupal installation, where settings.php is not at sites/default, we need to specify the site within our Drupal project that we want to bootstrap with the --uri option:
$ cd /home/juampy
$ drush --root=/home/juampy/projects/drupal --uri=mysite core-status
Drupal version : 7.29-dev
Site URI : other_site
Database driver : mysql
Database username : root
Database name : other_site
Database : Connected
Drupal bootstrap : Successful
Drupal root : /home/juampy/projects/drupal
Site path : sites/mysite
...
Summary
This chapter was an introduction to the principles of Drush. We covered the installation requirements so that you could set them up on your local environment and then proceeded with the installation of Drush.
Next, we went through some command-line basics that involved how to invoke commands, and how to append options and arguments as well. We saw some caveats regarding the order of options and arguments and suggested a structure to construct command invocations that is easy to read.
The last section of the chapter gave some tips on how to set the context of a Drupal project for Drush. We saw that Drush is pretty intelligent and can automatically figure out whether we are on a Drupal project in order to bootstrap it, or we can alternatively pass extra options to inform where our Drupal project is.
In the next chapter, we will go through one of the most important challenges of developing Drupal projects and how Drush can help us with it: keeping configuration and code together.