The Unix (Posix) shell is an window to the OS kernel. It is also an interface for the user for interacting with the Kernel that manages the hardware and all. The bootup process is considered ended when the shell is ready to be used. There are different varieties of the shell. The most important ones are: BASH, CSH, KSH, ZSH, FISHELL etc. There are no better manual on the web than the official bash manual which we have linked here.

BASH Software

  BASH MANUAL (HTML) 

BASH MANUAL (PDF)

CORE CONCEPTS (FOR TRAINING)

In this, we will assume the shell to be BASH for the sake of sticking to one shell.

Shell built-ins:

  Interview questions & discussions

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