How to: Create an entry into the update-alternative database

15. May 2020
howto linux terminal

There are situations where you have several programs for the same purpose or when you want to call a program by a different name. One such program is neovim, with the binary's name nvim. I'm using it of course as a drop in replacement of vim, alas I want to call it by that name. A natural way to accomplish this might be the creation of an alias in your shell like alias vim='nvim ', but this alias is only valid for the user, not system wide. Therefore it is not available when called with sudo.

For this reason (and many more) Debian introduced the concept of update-alternative. This, shortly spoken, allows for system wide aliases and can be created with update-alternative --install link name path priority. But I'm always kind of confused what those parameters mean. So, here's a short explanation:

  • link: The fully qualified path to the alias name, which should be created
  • name: The short name to call the binary
  • path: The fully qualified path to the actual binary
  • priority: In case there are several alternatives for this link/name you can choose a priority, how import this entry is.

As an example for neovim

sudo update-alternatives --install /usr/bin/vim vim /usr/bin/nvim 50

This means, that there should be a link under /usr/bin/vim that links to the real binary at /usr/bin/nvim and can be called by the short name vim. The priority 50 is some magic number I'm using, you can choose for your self.

Another example: fd on Ubuntu

The find alternative fd can be install via apt on recent Ubuntu versions. But as the name fd was already blocked by a different package, the binary's name is fdfind. To create a system wide alias to fd you can issue the following:

sudo update-alternatives --install /usr/bin/fd fd /usr/bin/fdfind 50

This creates at /usr/bin/fd a link to the binary /usr/bin/fdfind which can be called with fd. The great advantage to an alias is, that I can now also use sudo fd without any further configuration.