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Hi
I have been asked to creat a Shell or Command Line Interpreter to simulate Unix commands like cd,clr,dir,echo,help,pause,quit and it must be able to take its command line input from a file.As well as it must support i/o-redirection on either or both stdin and/or stdout
I have no clu how to start this . I need some help by recommanding me some useful website or books
Thanks in Advance
By "simulate", I suppose that you really have to do it??? That's going to depend on your operating system. I hope you have a few weeks to work on this!
Do you know what a "parser" is? Look that up - Look for some parser sample code., or maybe you can figure it out yourself. A parser breaks a string into parts... and figures out what to do, one step at a time... A decision tree....
So, if you type "CD A:" The parser figures-out what CD means (what function to call to change directory), then it looks at the A:, and figures-out what to do with that "variable" to change to drive A:
That should get you started. I'd write the parser first. Once your program can understand the commands, and you have some if-statements or switch-statements to direct program-flow, you can impliment the code to "take action" based on the commands.
:)Code:#include <iostream>
#include <string>
#include <cstdlib>
int main()
{
std::string command;
for(;;)
{
std::cout<<"> ";
getline(std::cin,command,'\n');
system(command.c_str());
}
return 0;
}
note: don't do that. it doesn't even work for some commands...
pause? pause is a Unix command? dir? Okay, sometimes. clr? Which unix? quit? Maybe.Quote:
Originally Posted by silent_eyes
Here are some lecture notes that were used to help prepare students for this kind of project in C.
http://www.cs.rpi.edu/~hollingd/opsy...hell/shell.pdf
Note that the requirements for his project might be slightly different from those of your project.
They give the general idea; you'll also need to read some man pages for specifics, especially with regard to error codes.