What is the difference between a built-in command and an external command in Linux?

In Linux, the difference between built-in commands and external commands is as follows:

1. Built-in Commands:

   • These commands are part of the shell itself (e.g., Bash, Zsh).
   • They are executed directly by the shell without needing to create a new process.
   • Examples include cd, echo, and exit.
   • Built-in commands are generally faster since they don't involve loading an external program.

2. External Commands:

   • These commands are separate executable files located in the filesystem (e.g., /bin, /usr/bin).
   • When executed, the shell creates a new process to run the command.
   • Examples include ls, grep, and cp.
   • External commands may take longer to execute due to the overhead of starting a new process.

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