Installer for composer by shell script

composer-installer.sh

#!/usr/bin/env bash
# Author Yannick Vanhaeren

curl -Ss https://getcomposer.org/installer -o composer-setup.php
sha384sum -c <<< "`curl -Ss https://composer.github.io/installer.sig` composer-setup.php"

if [ $? -eq 0 ]; then
    FILENAME="composer"
    
    if [ -n "$1" ]; then
        FILENAME="$1"
    fi
    
    mkdir -p /usr/local/bin
    php composer-setup.php --quiet --install-dir=/usr/local/bin --filename=$FILENAME
    RESULT=$?
    rm composer-setup.php
    exit $RESULT
else
    >&2 echo 'ERROR: Invalid installer signature'
    rm composer-setup.php
    exit 1
fi