A free program for Android, by MobilDev.

Shell Terminal Emulator is an application designed for your android phone. With the help of the app, you can use many available commands such as Linux/Unix on your Android device by accessing the Linux command line shell that is built into the operating system. Moreover,  You can create or remove files and directories, as well as browse your phone.

The  Shell Terminal Emulator application comes with a user-friendly interface for ease of navigation for every user. It also offers basic features for accessibility and controls to make its utilization free of hassle.