How to get list of PID's (like ps)

[mcnkevin]

Hi, im trying to write some code that will operate somewhat like ps but much simpler.

I need it so that The program will output all PID's and CMD names in the /proc filesystem (like ps -e).

I think i know how to get the CMD name once i actually have the PID, but my problem is I dont know how to get the PID's in /proc.

Is there some way of looping through all PID's? Even if someone could just direct me to somewhere in the kernel that does this so i can look at it and use it that would be great.

Thanks.

[mrjohnson]

Well, the `ps' command really just reads from /proc. The information there is from the kernel...

[mcnkevin]

So basically I just have to read through /proc?

So how would I do this in C and how would i get the PID from each entry in /proc?

[mrjohnson]

Well, I'd start with downloading a copy of procps and see how they did it. But the directories in /proc that are all numbers are your pids....