Without digging into the system's header files, you should be able to retrieve your current system's allowed number of processes per user with the command:

Code:

getconf CHILD_MAX

which is defined to return the system's current value for the maximum number of simultaneous processes per real user ID. Note that this says nothing about the size of the kernel's process table which must contain one slot for each process that is currently active. Note that in this case, active means has been started and its exit status has not yet been collected by its parent (or if its parent has died, collected by the system's garbage collector [a process named init on some systems]).

In the old days, the size of the process table was fixed when the kernel was built. Most of today's systems attempt to grow the pricess table as needed rather than failing fork()s when the process table fills up. But, if the kernel runs out of memory, a normal user's fork() will fail and a super-user's fork() may kill off a normal user's running process to allow the super-user to create a new process. What actually happens in these cases varies considerably from system to system.