I updated my comment above. If the computer is offline. Download the packages from a computer with an internet connection and store them on a USB drive.
In Debian and Ubuntu you can use `apt-get download nim`. Store the downloaded files on a USB drive. On the offline computer, after mounting and changing directory to the USB drive, you can then do `dpkg -i *.deb` (yes, Debian and Ubuntu use another utility called `dpkg` for doing local package management). Most if not all package managers can install loose package files (deb, rpm etc.) from disk as well. It will tell you when it misses a dependency. A more advanced way, but sometimes used because of security policies is creating your own package source (instead of one from the internet). You can also mirror an existing online package source on disk and use it offline. In debian you can use `apt-mirror` for that. **Note**: if you install packages you usually need to do it as `root` (like Administrator on Windows) or else it will tell you it failed. It is better to prepend every command that needs to be `root` with `sudo`. Example.: `sudo apt-get install nim`.
