For OS X and Linux:
Bring up Terminal, Bash, or your normal shell.
Type the following into Terminal/Bash:
# Download latest stable release using the code below or browse to github.com/drush-ops/drush/releases.
php -r "readfile('http://files.drush.org/drush.phar');" > drush
# Or use our upcoming release: php -r "readfile('http://files.drush.org/drush-unstable.phar');" > drush
# Test your install.
php drush core-status
# Make `drush` executable as a command from anywhere. Destination can be anywhere on $PATH.
chmod +x drush
sudo mv drush /usr/local/bin
# Optional. Enrich the bash startup file with completion and aliases.
drush init
For Windows:
C:\
Apache, PHP and MySQL
.
C:\xampp\apache\bin;C:\xampp\mysql\bin;C:\xampp\php;C:\drush;
drush status
bin
directory to the system path by placing export PATH="$HOME/.composer/vendor/bin:$PATH"
into your ~/.bash_profile (OS X) or ~/.bashrc (Linux).composer global require drush/drush
drush status
More details from Drush Docs