UNIX process id trace

[Tony Rems]

In article <2738 at dataio.Data-IO.COM> peterson at Data-IO.COM (Joe Peterson) writes:
>I have a simple question:
>
>Is there a way to get the parent process id of any arbitrary
>process id?  I know of getpid() and getppid(), but those only
>operate on the current process.
>
>I want to build a pid trace for the current process such as
>
>        long pidtrace[REALLYBIG];
>        long pid;
>        int i;
>
>        i=0;
>        pid = getpid();
>
>        while(pid != BOOTPROCESS)
>        {
>                pidtrace[i] = pid;
>
>                ++i;
>                pid = parentpid(pid);
>        }
>
>where parentpid() is the magic function that I can't find.
>
>Any ideas?
>
>Joe Peterson
>peterson at Data-IO.COM

You could cheat and do a popen of "ps".  Kernighan & Pike do it
in their zap program in "The UNIX Programming Environment". 

-Tony