I recently stumbled upon Nautilus Hide, an extension that adds a context menu option to hide / unhide files or folders without renaming them, and I decided to port it to Nemo file manager.
The extension hides files or folders without renaming them (without adding a dot prefix or a tilde suffix), by adding them to a file called ".hidden", which can be used by most major file managers to hide files.
This can be done manually (I wrote an article about it a while back), and is supported by most file managers - by creating a file called ".hidden" and adding the file and folder names you want to hide to this file. This extension is for those that need to do this frequently or set up Ubuntu / Linux Mint for someone inexperienced who wants such a feature.
To use this extension to hide a file or folder, simply right click the file/folder and select "Hide file":
To unhide a file or folder, press Ctrl + H (this displays hidden files and folders), then right click the file you've previously hidden, and select "Unhide". Then press Ctrl + H again to hide hidden files and folders.
This obviously only works for files hidden by adding them to a file called ".hidden", and it doesn't work with files that have a dot prefix or a tilde suffix.
Install Nemo Hide / Nautilus Hide
Nemo Hide is available in the Nemo 2.x and Nemo 3.x (with Unity patches) WebUpd8 PPAs. If you use Nemo from any of these two PPAs, simply run the commands below to install Nemo Hide:
sudo apt update
sudo apt install nemo-hide
The WebUpd8 Nemo PPAs are not compatible with Linux Mint (because the packages can overwrite Nemo for Cinnamon with Nemo for Unity) or Nemo from the official Ubuntu repositories, but this extension is. So if you use Linux Mint or Nemo from the official Ubuntu repositories, you can grab the Nemo Hide deb (or source) from HERE.
Once installed, restart Nemo:
nemo -q
The Nautilus Hide extension is available in the official Ubuntu repositories so if you use Nautilus, install it using the command below:
sudo apt install nautilus-hide
Once installed, restart Nautilus:nautilus -q
Note that the Nautilus Hide version from the Ubuntu repositories doesn't automatically refresh folders, so after hiding a file, you'll need to refresh the folder by pressing F5. The latest Nautilus Hide does this automatically.