[simran]

I was wondering if there is any way to get the PIDs of all the processes from the user-written code. I know that we can use the getpid() and getppid() to get the code for the current process and its parent. However, is there a way to get the PIDs of all the processes on the system? (source code for 'top'?

------------------

[IamBob]

"man ps"

[parallax]

You could get the source code for top and try to manipulate the kvm functions... however, this is cumbersome.

Try a pipe to "ps" with arguments "wwwaux" (All processes, full name, &c.) Then scan the string to your liking.

[lindberg]

Look at sysctl() ("man 3 sysctl"). More specifically, the CTL_KERN top-level name, and the KERN_PROC section under that.

[lindberg]

[Double post]

[This message has been edited by lindberg (edited 04-24-2001).]

[simran]

Thank you for all your suggestions. I am looking at syscntl(). This seems to be useful. It has some really low level (neat) stuff which we can poke into. I am not sure, however, what permissions will my process have to have in order to read some of these variables. I will try and see how far will I get.

[simran]

Is there a way to use the unix shell command from a C source? If yes, then I guess, piping the ps to a string will suffice. If not, then I probably have to us syscntl().

Thank you.

[Angus_D]

here's some code I wrote a while ago just for learning how to use popen(). It's messy and probably lame, but hey, I think it kinda works

It uses ls but you can easily change this to your liking.

Code:
#include <stdio.h>
#include <stdlib.h>

int main(void)
{
        int i;
        FILE *f;
        int c;
        char s[2500];

        f = popen("ls","r");

        if (f != NULL)
        {
                char mychar;
                for (i=0; i<2500; i++)
                        if (!(feof(f)))
                                s[i] = fgetc(f);

                printf("%s",s);

        } else {
                printf("Something went wrong somehwere.");
        }

/*      i = system("ls");*/

        i = pclose(f);

        return 0;
}

[simran]

Thanks Angus. I tried the code. It works. Thank you all for the help.