When attempting to use composer you get the following error:
Composer could not find a composer.json file
This happens when you are working within a directory that does not contain a composer.json file.
The most common cause for this error is when you are attempting to use composer in the wrong directory. Before considering the possibility of other causes, make sure that you are in the correct directory first. Check the Resolution section below for advice about determining the cause of the error.
The other two most common causes for this would be that you either have not yet installed your application or if you are building a new application from scratch, you have not yet manually created your composer.json.
First, make sure that you are in the correct directory with the following steps.
1. If you are installing an application or framework, be sure to review the installation instructions to see if there are any specific notes about which directory should be used.
If there are no specific instructions regarding the particular directory to use, you may typically install your application to the document root of your domain.
2. To find the document root of your domain, log in to your cPanel account and click on the Domains icon. The document root directory is specified on that page.
3. Once you find the correct directory, (use the document_root if you are unsure) you should then add composer to your users PATH. To do this, go back to the main cPanel page and click on the Terminal icon which is under the "Advanced" section.
4. On the black command line that you see in the "Terminal" icon, paste the following command and then press the Enter or Return button on your keyboard:
echo "source /etc/profile.d/cpanel-php-composer.sh" >> ~/.bash_profile
5. Then in the same command line, type the exit command, and then press the Enter or Return button on your keyboard:
6. Then click the blue "Reconnect" button to reconnect to the command line with the new changes from the ~/.bash_profile that you have edited
That change will allow you to use Composer on the command line easily.
7. Now use the cd command to change to the directory that is specified by either your application installation instructions or the document root of your domain. The following example command changes to the public_html directory which is the default document root for the primary domain of a cPanel account. You may or may not be using this for your domain depending on your specific situation. Please use the steps above to find your correct directory to use:
8. Now either use the installation instructions for your application to install the composer.json file and other application files. Or if you are creating your own application from scratch, you can use the official Composer documentation to learn how to create a new composer.json file:
As a courtesy cPanel also has a guide for installing Magento, which requires composer: