Installing composer using curl

composer-install.sh

# Goto a directory you can write to:
cd ~

#get composer:
curl -s https://getcomposer.org/installer | php
# move composer into a bin directory you control:
sudo mv composer.phar /usr/local/bin/composer

# double check composer works
composer about

# (optional) Update composer:
sudo composer self-update

First install php then try to run this command
curl -sS https://getcomposer.org/installer | sudo php -- --install-dir=/usr/local/bin --filename=composer

curl -sS https://getcomposer.org/installer | php -- --install-dir=/usr/local/bin --filename=composer

Will failed with error: The installation directory "/usr/local/bin" is not writable. So, need run php with sudo:

curl -sS https://getcomposer.org/installer | sudo php -- --install-dir=/usr/local/bin --filename=composer

Usage: php
php -[b|c|n|h|i|q|s|v|?] [] [args...]
Run in LSAPI mode, only '-b', '-s' and '-c' are effective
Run in Command Line Interpreter mode when parameters are specified

-b address:port| Bind Path for external LSAPI Server mode
-c | Look for php.ini file in this directory
-n No php.ini file will be used
-h This help
-i PHP information
-l Syntax check
-q Quiet-mode. Suppress HTTP Header output.
-s Display colour syntax highlighted source.
-v Version number
-? This help

args... Arguments passed to script.
curl: (23) Failure writing output to destination