I have just installed composer in my /usr/bin folder, so when from that folder I run php composer.phar I get the help info about composer. But, whe
You can do a simple global install to run it from anywhere
curl -sS https://getcomposer.org/installer | php
mv composer.phar /usr/local/bin/composer
The https://getcomposer.org/doc/00-intro.md#globally website recommends this way. Worked well on Ubuntu 14.04 no problem.
This way you don't need to do as an example php compomser.phar show , you just do composer show , in any directory you are working with.