Debian (.deb) packages are the packages that are used in Ubuntu. You need to have administrative privileges to install a .deb file.

To install .deb files from shell/command prompt you can use the dpkg command. dpkg is a package manager for Debian based systems. It can install, remove, and build packages, but unlike other package management system’s it can not automatically download and install packages and their dependencies.

We were duplicating a Magento install, so we copied Magento source code from live server to the new server. We had Ubuntu in our new servers. After setting up new server we noticed that Magento cache and sessions files were created in /tmp/ Ubuntu folder.

When we took backup of live server we had excluded the var folder. While debugging we noticed that {{MAGENTO_ROOT}}/var folder was not created because of permission issue. So, we created the {{MAGENTO_ROOT}}/var folder and set its permissions to 777. The issue got resolved.