7 replies to this topic

[lhy990084]

1.the command line interpreter checks whether the input command line matches a pre-defined lanaguage or not..If yes the os shell checks and invokes the programs specified in the input command line..else wait command line..
2.process creation..
Find the programs..with absolute path or relative path
3.i/o redirection
Rule [command name][arg]*<[filename]
4. detecing process termination and susupension.

5. signal handling.. such as Ctrl+Z and Ctrl+C

that are some problems..i cant solve it... finding help plz..>.< can some one gives me some hints..or some pseduo code...or lay out..i am stumming on it.now

[dargueta]

This sounds a lot like homework. Try to come up with a plan, and at least show us that. Pseudocode isn't really that difficult to come up with. What OS are you compiling for?

[G_Morgan]

dargueta said:

This sounds a lot like homework. Try to come up with a plan, and at least show us that. Pseudocode isn't really that difficult to come up with. What OS are you compiling for?

Sounds like a Unix.

Best option is to look up the POSIX system calls.

[WingedPanther]

Another question is: what commands will you support? Will you be displaying error messages?

It looks like you haven't fully posted your instructions, either. For example, while this is a definition of a shell, it doesn't indicate whether you must create a shell, write a paper on those aspects of a shell, or something else.

[lhy990084]

yes it is on UniX.. i dont how to write.. (when user typing some command which is correct or not..if correct the process creation.. it give some tips for me .. (use fork system call and exec system call..) but i have type many time..i cant do it..

[dargueta]

So you don't know what commands you're going to support? Come up with a list of the ones you use most often, and support those. Pick maybe 10 at most to begin with.

[WingedPanther]

Basically: you have to
1) accept a string
2) be able to parse the string to determine what should be done
3) determine if any of the involved commands return an error (does not exist or fails on the input)

I would start with something simple, like supporting basic commands such as ls, mv, etc.

[Aereshaa]

The way to actually do that is to fork(), and then in one process, execl() another program.