/proc/ in iOS? Or rather, why is it absent from the root directory structure?
It's typically a crucial interface to the kernel of any UNIX-like operating system; what else is in place to assume this role?
FYI: Following is the main system information and root directory structure of the device in question.
iPhone:~ mobile$ uname -a Darwin Kernel Version 14.0.0: Wed Jun 24 00:46:37 PDT 2015; root:xnu-2784.30.7~30 RELEASE_ARM_S5L8950X iPhone5,2 N42AP
iPhone:~ mobile$ find / -maxdepth 1 / /.Trashes /.file /.fseventsd /.ppuntether_inst /Applications /Developer /Library /System /User /bin /boot /cores /dev /etc /lib /mnt /ppuntether /private /sbin /tmp /usr /var