Can Linux apps be run in Android?

Android is based on Linux; can native Linux applications be run on Android?

Answer

In general, no. Android apps generally run in a sandboxed Java-like virtual machine, so have to be written in Java or some language that compiles to virtual-machine bytecode that use the Android API.

However, the virtual machine does run on top of the underlying Linux OS, and there are ways to call native code. See https://developer.android.com/tools/sdk/ndk/index.html

So, while it is technically possible to run native Linux programs, as there is a Linux kernel running beneath everything, most users would not be able to install such applications or use them. (If you have root access or are building your own firmware, then you can do whatever you want.)