Error when running composer:
composer
/usr/bin/env: php: No such file or directory

Probably, php-cli is not installed. Try:
Centos:
yum install php5-cli
Ubuntu:
sudo apt-get install php5-cli

More probably, php5-cli is installed but not found in $PATH. Find out where is the php/bin folder and try:
export PATH=”$PATH:/path/to/php/bin”