You can use the help command for other builtins too.
也可以用help命令了解其他内置命令。
2
Bizarre Python Import Issue - Relative Imports of Builtins?
奇怪的巨蟒进口问题-内部相对进口？
3
The bash shell contains two types of commands: builtins, which are internal, and external programs (or external filters and commands), which are typically self-contained binary program files.