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BASH (Bourne Again Shell)

COMMAND LINE --- HOME --- UNIX PHILOSOPHY

  • Command language interpretor for Linux.
  • Developed by GNU Project.
  • Backward compatible with sh shell.
  • Incorporates features from Korn Shell and C Shell.

Shell Commands

  • Internal Commands : (Built-in) part of shell itself.
  • External Commands : Seprate binaries stored in specific directories.

BASH + Command Types

  • Aliases (such as ll)
  • Keywords (such as if)
  • Functions
  • Built-In (such as pwd)
  • Files (such as /bin/date)

type command

Used to find out if a command is built-in or an external binary.

type -a COMMAND

Returns built-in, if the command is internal; Returns path of command in case of external.

Kernel : Core of any Operating System.

Shell : Provide interface b/w User and Kernel.

Terminal : Allow users to enter command & display back results.