Mastering Linux Alternatives: Switch and Manage Multiple Software Versions Easily

Basic Concept

The alternatives command is a shorthand for update-alternatives. It manages symbolic links (e.g., in /usr/bin) that point to the user‑selected default program version. It is available on Debian‑derived distributions and many other Linux families.

Installation

On Debian‑based systems ensure the package is installed:

sudo apt-get update
sudo apt-get install alternatives

On RPM‑based distributions (Red Hat, Fedora, CentOS) the tool is provided by the chkconfig package and is installed by default.

Adding a New Program Version

Register a new alternative by specifying the generic link, the name, the target binary, and a priority. Example for Python interpreters:

sudo alternatives --install /usr/bin/python python /usr/bin/python3.8 100
sudo alternatives --install /usr/bin/python python /usr/bin/python3.9 200

In this example /usr/bin/python is the generic path, python is the alternative name, the two target binaries are the actual executables, and the numeric values are priorities (higher = preferred).

Viewing and Selecting Versions

List all alternatives for a name: sudo alternatives --display python Switch the default interactively: sudo alternatives --config python The command prints each registered version with its priority and a selection number.

Automatic vs Manual Mode

In automatic mode the system selects the highest‑priority alternative. In manual mode the user‑chosen version is kept even if a higher priority is added. Change the mode with:

sudo alternatives --auto python   # automatic
sudo alternatives --manual python # manual (if supported)

Removing an Alternative

To delete a specific target from the alternative set:

sudo alternatives --remove python /usr/bin/python3.8

Summary

Using alternatives allows precise control over multiple versions of a program, simplifying maintenance and ensuring the intended binary is invoked.