About us
Learmux is a small publication about Termux, Android's terminal and Linux environment, and about the command line in general.
What this is
Most command-line tutorials stop at listing commands. Learmux pairs each short lesson with a
challenge that makes you use it. You read about grep, then you pull a flag out of a
noisy log with it.
Everything is designed for a phone first, because that is where Termux lives. It works just as well on a laptop.
Who makes it
Learmux is designed, built and maintained by Apsides Labs, an independent research and engineering studio. We build software that teaches.
The studio builds for people who have the least. The slowest connection, the oldest device, the smallest budget. So its work is offline-first and CPU-only wherever it can be. Learmux follows the same rule. Static pages, no tracking, no account, and nothing that needs a server.
How the sandbox works
There is no operating system behind the terminal, and nothing you type reaches a real shell. Each challenge declares a virtual filesystem, and your keystrokes go through a command parser written for this site. The same command always gives the same result. Resetting a challenge puts the original files back.
Commands that would normally touch a network or the device, such as nmap,
curl, pkg and ps, return output written for that challenge.
Nothing depends on a server.
How challenges are validated
Completing a challenge is decided by explicit rules stored with the challenge, not by scanning for a flag string. A rule might require that you read a particular file, run a particular command, or move into a particular directory. Submitting the flag directly also works.