Bash te fournit le PID du processus:
johand@horus:~$ ls -l > /dev/null &
[1] 21691
Dans ton code C, tu peux faire appel à getpid
man 2 getpid
NAME
getpid, getppid - get process identification
SYNOPSIS
#include <sys/types.h>
#include <unistd.h>
pid_t getpid(void);
pid_t getppid(void);
DESCRIPTION
getpid() returns the process ID of the current process. (This is often
used by routines that generate unique temporary file names.)
getppid() returns the process ID of the parent of the current process.
CONFORMING TO
POSIX, 4.3BSD, SVID
Gates gave you the windows.
GNU gave us the whole house.(Alexandrin)