are commonly thought of as command-line interfaces (CLI). Commands can be typed in one at a time, or a script
can be used to execute a string of commands. However, it can refer to a graphical shell provided by a graphical user interface (GUI). Shells are often used to invoke or "launch" another program; additionally they can have capabilities such as viewing the contents of directories.
is the default shell, which in 1.0.5 and 1.0.6 is ash or bash
(In 1.0.6, SHELL seems to point to bash, but the command line seems to nevertheless default to ash.)
is the simplified BusyBox
version of bash (BusyBox
v0.60.5 in 1.0.6)
Bash has become a de facto standard for shell scripting on all flavors of UNIX.
The bash is GNU bash 3.00.0(1) in 1.0.6.
Advanced Bash−Scripting Guide. An in−depth exploration of the art of shell scripting.