Guide to Linux, developed by Essence Infotech, is a free education and reference app available on Android devices. This app provides a comprehensive tutorial to learn and explore the Linux environment along with its commands and shell scripts. The app includes details of all basic and advanced commands of Linux, along with their syntax and examples. Moreover, it has a dedicated module for Shell Script learning.

One of the best features of this app is that it works offline, enabling users to learn and explore Linux anytime, anywhere. The app also integrates the Linux Terminal, which is referenced from the original Jack Palevich Terminal Emulator available on the Play Store. However, it may conflict with other terminal emulator apps, which the user may have to remove.

Overall, Guide to Linux is an excellent resource for those who want to learn Linux or improve their knowledge of Linux commands and shell scripts.