Thread: problem with looping

I'm preparing to make a very simple linux shell in c (one that will just run one program with any required arguments and perhaps later might search for the program in a path variable if its not found in the working directory).

Anyway I thought since its currently well above my skill level in C I would learn to play with loops since thats pretty much what the shell will be doing wont it?


#include <stdio.h>
#define SENTINEL -1 // to be implemented later.

int main()
{
char v[256];
char command;
do
{
fgets(v, 256, stdin);
system(v);
} while (fgets(v, 256, stdin) != NULL);
}

my intention is that if the user enters just '\n' without anything else or 'sentinel' is typed (-1) then the code will no longer loop otherwise it will indefinently run commands for the user I've tried heaps but cant seem to make anything work..

Originally posted by razza
my intention is that if the user enters just '\n' without anything else

So you need to check for a \n at the beginning of your buffer.

Code:

#include <stdio.h> 
#define SENTINEL -1 // to be implemented later. 

int main() 
{ 
	char v[256]; 
	while(fgets(v, 256, stdin) != NULL && v[0] != '\n')
	{ 
		system(v); 
	}
}

Cheers,
Monster

thanks buddie!

I really appreciate the help.

You may need to remove the \n from the buffer before passing it to system()