沙盒

Bash is an acronym for ‘Bourne-Again SHell’. The Bourne shell is the traditional Unix shell originally written by Stephen Bourne. All of the Bourne shell builtin commands are available in Bash, The rules for evaluation and quoting are taken from the POSIX specification for the ‘standard’ Unix shell.

This chapter briefly summarizes the shell’s ‘building blocks’: commands, control structures, shell functions, shell parameters, shell expansions, redirections, which are a way to direct input and output from and to named files, and how the shell executes commands.

Shell Syntax:	What your input means to the shell.
Shell Commands:	The types of commands you can use.
Shell Functions:	Grouping commands by name.
Shell Parameters:	How the shell stores values.
Shell Expansions:	How Bash expands parameters and the various expansions available.
Redirections:	A way to control where input and output go.
Executing Commands:	What happens when you run a command.
Shell Scripts:	Executing files of shell commands.