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Shell vs Bash

Shell​

  • Shell is a program that acts as an interface between you and the Linux OS.
  • It takes your commands and tells the kernel what to do.
  • There are many types of shells.

Examples of shells:​

  • sh (Bourne Shell)
  • bash (Bourne Again Shell)
  • zsh
  • fish
  • ksh

Think of Shell as a category.

Bash (Bourne Again Shell)​

  • Bash is one type of shell.
  • It is the most commonly used shell in Linux.
  • Default shell in most Linux distributions (Ubuntu, Debian, etc.).
  • Has more features than older shells.

Think of Bash as a specific shell inside the shell family.

Difference Table​

FeatureShellBash
MeaningInterface to OSA type of shell
TypeGeneral conceptSpecific implementation
Examplessh, bash, zsh, fishbash only
Default in LinuxDepends on distroUsually default
Script supportBasicAdvanced (arrays, loops, history)
File/bin/sh/bin/bash

Simple Analogy​

  • Shell = Vehicle
  • Bash = Car

(A car is a type of vehicle, just like Bash is a type of shell.)

Check what shell you are using​

echo $SHELL
ps -p $$

To see all available shells on your system​

cat /etc/shells

.bashrc vs .bash_profile​

  1. .bash_profile runs once when you log in to your system.
  2. .bashrc runs every time you open a new terminal.
  3. .bash_profile is used for login setup and environment variables.
  4. .bashrc is used for aliases, shortcuts, and terminal behavior.
  5. Usually, .bash_profile loads .bashrc using source ~/.bashrc.

source vs . (dot)​

  1. source and . do the same thing — they run a file in the current shell.
  2. source file.sh and . file.sh are completely equivalent.
  3. Changes (variables, aliases) remain active after execution.
  4. source is more readable; . is shorter and POSIX-standard.
  5. Example: 
    source ~/.bashrc
    . ~/.bashrc
  6. source is a bash built-in command.
  7. The file must be readable. 
    chmod +r file.sh