Magento 2.0 Missing Write Permissions in Directory var When Run bin/magento setup:upgrade

Hello,

Recently in of our Magento product we installed a Payment Gateway module on our Magento for that we have to run following command.

php bin/magento setup:upgrade php

But every time we run this command we end with following exception.

Missing write permissions to the following directories: public_html/var

so at first it looks like write permission issue in directory, so we gave write permission to directory

chmod 777 ./var

And command run successfully but still we were getting same error while running

php bin/magento setup:upgrade php

That was little wired as we have all the necessary permission but still command was not working. So I decided to get error location and found out following file from where this error is thrown.

setup/src/Magento/Setup/Model/Installer.php

Open this and find following function.

/**
     * Check permissions of directories that are expected to be writable for installation
     *
     * @return void
     * @throws \Exception
     */
    public function checkInstallationFilePermissions()
    {
        $results = $this->filePermissions->getMissingWritableDirectoriesForInstallation();
        if ($results) {
            $errorMsg = "Missing write permissions to the following directories: '" . implode("' '", $results) . "'";
            throw new \Exception($errorMsg);
        }
    }

This is the function which throws an error so what I did is I commented all the code in this function and run the command again

php bin/magento setup:upgrade php

and it worked, it updated properly and after that I again uncommented this code and upload file back to server.

PLEASE NOTE THIS IS A HACK, AS A MAGENTO DEVELOPER I DO NOT SUGGEST TO UPDATE SOURCE FILE BUT THERE WAS NO OTHER OPTION SO I TRIED IT. IF YOU ARE TRYING THIS ON YOUR SIDE, PLEASE BE CAREFUL.