如何找到最后打开的文件描述符？

Question

Consider I have a process called a.out , In that process, i have opened the 10 files using a open() function.

Consider that time I get the last descriptor is 13. So I need to know is there is any way to find the last opened descriptor in the process.

For that I am using a getrlimit like this

   if(getrlimit(RLIMIT_NOFILE,&r1)<0)
              perror("error");

But when I am priting this I get 4096 in my system. SO Is there is any way to do this?

Answer 1

There is no (sensible) magic way to do this. You must remember it in a variable somewhere. Each time you open a file, update this variable.

( getrlimit with RLIMIT_NOFILE tells you how many files you can open, not how many you have opened).