Save "Home" page one more time and it will reset cache for this page.
Or, if you want to do it programmatically, clear cache by tag
[\Magento\Cms\Model\Page::CACHE_TAG . '_' . $page->getId()]
this is not about operating system, this is only permissions.
if your webserver/php user is nobody, then you better run all commands as nobody.
su -c "Your command right here" -s /bin/bash nobody
sudo su -c "Your command right here" -s /bin/bash nobody
su nobody -s /bin/bash -c "Your command right here" -s /bin/bash