On 21 Oct 2002, Nikhil Karkera wrote:

If I rum a simple shell script, the bash above, doesn't execute it. It invokes another bash process only for the execution of this script.

You need to first understand how a process is executed in unix. There is no way to create a new process. The only thing that can be done is to fork, and then exec the new process.

Whenever you enter a shell command, if it is not internal to the shell, the shell will fork and exec the new command. The same thing happens when you run a shell script.

shell scripts are interpreted, therefore they need an interpreter to be run - bash in this case.

When you run a script (any script), the shell reads the first few bytes of that script and then execs the interpreter specified after the #!.

To tell the shell not to fork and exec, you can do use .

. shell_script

This tells the shell to execute the script within the current shell, and not to spawn a new subshell.

Philip