
Since the new version of drush has come out and now requires Composer, most of the guides I've seen online don't work anymore. Hopefully, this guide will prevent others from the headaches I went through getting this setup on my host.
First, I'm assuming you already have SSH access to your host. If not, go get that done and come back to install drush. It will be a little different depending on your hosting provider.
Make sure you're in your home directory
cd ~
Next, download Composer to your home directory
wget https://getcomposer.org/installer
You should now have the installer downloaded to your home directory in a file called 'installer'. Since most hosting providers are still default to php5.2, we need be sure we are using php5.3 or higher. On my host, I was able to use the cpanel to upgrade to php5.4. Confirm your php version with this command
php --version
You should have something like this show up.
PHP 5.4.28 (cgi-fcgi) (built: May 5 2014 00:18:15) Copyright (c) 1997-2014 The PHP Group Zend Engine v2.4.0, Copyright (c) 1998-2014 Zend Technologies with Zend Guard Loader v3.3, Copyright (c) 1998-2013, by Zend Technologies
If that didn't work try someting like this. On HostGator, the upgrade did not affect the home directory. I was able to do this with this command. "/opt/php53/bin/php" is the path to php5.3 it may be different on different servers. Confirm with something like this if your path was like I said earlier.
/opt/php53/bin/php --version
Sometimes it can be something like this. this is an example for running drush on BlueHost shared hosting
/usr/php/54/usr/bin/php-cli --version
Be sure it says PHP 5.3 or higher before continuing...
Install Composer
php -f installer
Now download drush. You may need to add the "--no-check-certificate" at the end to work properly...
wget https://github.com/drush-ops/drush/archive/master.zip
Unpack the zip file
unzip master.zip
That puts a directory callded 'drush-master' with all the drush goodness in it. Change the name to just drush and go there.
mv drush-master drush cd drush
Install Composer dependencies. There may be some tricks that will need done to get around the lack of "CLI" for php on shared hosting. One way is to check if you can use the "php-cli" command. Check with "php-cli --version". If you get back a non-error message. You should be good to do with this command.
php-cli ~/composer.phar install
If that isn't working, you can get around it with something like this.
/opt/php53/bin/php ~/composer.phar install
Navigate back to your home directory. And run drush
cd ~ drush
If you get errors, there could be lots of things that went wrong. If you needed to specify a different php version earlier, you probably need to add an alias. Find your .bash_profile file at the end if you needed to use a specify another php version.
Edit your .bash_profile file to update your aliases to the drush command. Here is the command.
nano .bash_profile
Add something like this to your file. You may need to do something different. This one worked on HostGator. Remember the step several above where we got the php version replace the "/opt..../php" stuff with what worked in this line.
alias drush="DRUSH_PHP=/opt/php53/bin/php ~/drush/drush"
The one for BlueHost looked like this
alias drush="DRUSH_PHP=/usr/php/54/usr/bin/php-cli ~/drush/drush"
You can double check your drush version like this when everything is working.
drush --version
If everything is good, it should report back somethign like this
Drush Version : 7.0-dev
Hope this helps.