Hey all, I would like to know how an interpreter (like bash, cmd) interpret scripts (like a batch file) and execute the commands.
I know how the fundamentals of how it is done. But I'd like an in dept description, of the process.

(I require this information for my little shell (CLI) project in currently doing)
Thanks in advance!

MeshNix,

It depends on how complex your CLI script language is.

Well it's quite straightforward even for complex shells. The only difference is that they have many more features and are much more flexible than simpler ones. It's not about "more black magic".

The basic principle is the same: the script file is read and parsed like an assembler/compiler does, but here, every command is executed "live" as if the user was entering them. It may execute internal commands or external programs. It may also support branching, control statements, read/writing environment variables, its own variables, data structures, etc.
In Unix shells, the script may not be executed by the shell itself. The first line (the shebang) defines the interpreter to be used, which might not be the same shell or even *a* shell, but python or perl.

Start small. For example, only support two internal commands.
Then check how other things are done by reading source code and implementing your own routines.

baldr,
My shell basically supports commands that allow for data manipulation, like array splices, and things of that sort.

ManOfSteel,
Thanks! I've started designing my shell. My shell basically supports on-line processing, and batch processing. But, I have found few source codes (in assembly). But not that are to complex. Do you know any links where i can find any?