How do builtins differ from commands?

Builtins differ from commands in the following ways:

1. Execution Context:

   • Builtins: Executed directly within the shell process. They do not require a separate executable file.
   • Commands: Typically refer to external programs or scripts that are executed in a new process.

2. Performance:

   • Builtins: Generally faster since they avoid the overhead of process creation.
   • Commands: May take longer to execute due to the need to spawn a new process.

3. Functionality:

   • Builtins: Often provide essential shell functionalities, such as changing directories (cd), setting environment variables (export), or controlling shell behavior (set).
   • Commands: Can be any executable program or script, including user-defined scripts, utilities, or system commands.

4. Availability:

   • Builtins: Available in the shell regardless of the current working directory.
   • Commands: Availability depends on the system's PATH and whether the executable is installed.

In summary, builtins are integral to the shell's operation, while commands are external programs that can be executed from the shell.