Install Composer

Install Composer on Ubuntu

[1. Install dependencies]
sudo apt install curl php php-mbstring php-xml

[2. Create an installation and temporary directory for Composer]
sudo mkdir -p /opt/Composer mkdir -p ~/Composer

[2. Download the installer script]
cd ~/Composer
php -r "copy('https://getcomposer.org/installer', 'composer-setup.php');"

[3. Verify the integrity of the installer script]
(Stores the latest signature of the installer script)
HASH="$(curl -Ss https://composer.github.io/installer.sig)"

[Verify the installer script]
php -r "if (hash_file('SHA384', 'composer-setup.php') === '$HASH') { echo 'Installer verified'; } else { echo 'Installer corrupt'; unlink('composer-setup.php'); } echo PHP_EOL;"

You should get the following output
Installer verified

If you get the output Installer corrupt, then you will need to redownload the installer script and rerun the verification command above.

This installer script will simply check some php.ini settings, warn you if they are set incorrectly, and then download the latest composer.phar in the current directory.

[4. Install Composer]
php composer-setup.php --filename=composer

[Installing a specific version of Composer]
php composer-setup.php --version=<version_no>

e.g. php composer-setup.php --version=1.9.1 to install Composer 1.9.1
All available versions can be found here https://getcomposer.org/download/

[5. Move Composer to a protected directory]
sudo move composer.phar /opt/Composer/composer.phar

[6. Add the composer binary to your $PATH]
echo "export PATH=\"/opt/Composer/:\$PATH\"" >> ~/.bash_profile

[7. Reload the changes]
source ~/.bash_profile

[8. Cleanup the temporary directory]
rmdir ~/Composer

[9. Verify the installation]
composer --verson
(An output showing the installed Composer version will be displayed)

[Updating Composer]
(This will update Composer to the latest stable version)
composer self-update

[Upate to a specific version of composer]
php composer self-update <version_no>

e.g. php composer self-update 1.9.1 to update to Composer 1.9.1

Tunji Olu-Taiwo