If set a new process is created; otherwise changes affect the current process.
If set, the child process will be dissociated from the parent. Upon exit the child will not leave a status for the parent to collect. See wait(2).
If set, the invokers file descriptor table (see intro(2)) is copied; otherwise the two processes share a single table.
If set, the new process starts with a clean file descriptor table. Is mutually exclusive with RFFDG.
If set, the kernel will force sharing of the entire address space, typically by sharing the hardware page table directly. The child will thus inherit and share all the segments the parent process owns, whether they are normally shareable or not. The stack segment is not split (both the parent and child return on the same stack) and thus rfork with the RFMEM flag may not generally be called directly from high level languages including C. May be set only with RFPROC. A helper function is provided to assist with this problem and will cause the new process to run on the provided stack. See rfork_thread(3) for information.
If set, the kernel will force sharing the sigacts structure between the child and the parent.
If set, the kernel will return SIGUSR1 instead of SIGCHILD upon thread exit for the child. This is intended to mimic certain Linux clone behaviour.
File descriptors in a shared file descriptor table are kept open until either they are explicitly closed or all processes sharing the table exit.
If RFPROC is set, the value returned in the parent process is the process id of the child process; the value returned in the child is zero. Without RFPROC, the return value is zero. Process ids range from 1 to the maximum integer ( int) value. The rfork system call will sleep, if necessary, until required process resources are available.
The fork system call can be implemented as a call to rfork "RFFDG | RFPROC" but is not for backwards compatibility.
The system-imposed limit on the total number of processes under execution would be exceeded. The limit is given by the sysctl(3) MIB variable KERN_MAXPROC. (The limit is actually ten less than this except for the super user).
The user is not the super user, and the system-imposed limit on the total number of processes under execution by a single user would be exceeded. The limit is given by the sysctl(3) MIB variable KERN_MAXPROCPERUID.
The user is not the super user, and the soft resource limit corresponding to the resource argument RLIMIT_NOFILE would be exceeded (see getrlimit(2)).
Both the RFFDG and the RFCFDG flags were specified.
Any flags not listed above were specified.
There is insufficient swap space for the new process.