[c/c++] Run scripts

aalex77 · 05-06-2006, 09:52 AM

Hello everybody, i need to write a little program that allow me to run a linux script.

I did something like that

Code:

#include "string"
#include "iostream"
#include "fstream"

#define PIPE "/tmp/pipe"
using namespace std;

int main() 
{
    FILE *fp;
	ifstream c1;
	char *command;
	while(1)
	{
		c1.open(PIPE);
		sleep(1);
		if(c1.is_open())
		{
			command = new char[256];
			while(!c1.eof())
			{
				c1.getline(command,256,'\n');
				system(command);
			}
			sleep(1);
			c1.close();
			remove(PIPE);

		}
	}	
}

and the main program write the name of the script in a pipe file.

but when i make ps , further my process i can see two line like this

Code:

3405 root        496 S   sh -c /myfolder/myscript
 3406 root        528 S   /bin/sh /myfolder/myscript

anyone can explain me why

Regards

jschiwal · 05-06-2006, 11:05 AM

You should read the command(3) man page.

Quote:

DESCRIPTION
system() executes a command specified in command by calling /bin/sh -c
command, and returns after the command has been completed.

aalex77 · 05-06-2006, 12:36 PM

Well, the loop works, but the 2 process don't want to die

Maybe does exist a better way to get the goal??
Thanks

jschiwal · 05-06-2006, 01:51 PM

Does your script terminate if you start it normally?

Also, don't compile and run your sample programs as root. That's too dangerous.

aalex77 · 05-06-2006, 02:30 PM

Actually is an executable file that's run on an embedded system, and if i start my script with a telnet session works pretty good.

jschiwal · 05-06-2006, 02:48 PM

I'm guessing that it is because the script is running in the background and expecting input from /dev/stdin or writing output to /dev/stdout which is blocking it. So that is the reason it doesn't finish, is because it uses a command that prints and that is blocking it.
Any command that produces output should have the output redirected to /dev/null or to a file or piped to a command that uses the output.

aalex77 · 05-06-2006, 02:55 PM

thanks, i'll try to redirect the output then!
Regards