A kind of shell, written by Brian Fox in 1987 for GNU project. The first official version was published in 1989. It was originally planned to be used on GNU operating system, but it can run on most Unix-like operating systems, including Linux and Mac.

OS X v 10.4 all use it as the default shell.

Bash is a command processor, which usually runs in a text window and can execute commands directly input by users. Bash can also read commands from files called scripts. And other Unix

shell

Similarly, it supports file name substitution (wildcard matching), pipeline, here document, command substitution, variables, and structural control statements of conditional judgment and loop traversal. Basic functions, including keywords and grammar, are borrowed from sh. Other functions, such as historical commands, are borrowed from csh and ksh. Generally speaking, Bash is a POSIX-compliant shell, but it has many extensions.