fork - create a copy of this process
integer function fork()
Fork creates a copy of the calling process. The only distinction
between the 2 processes is that the value returned to one of them
(referred to as the 'parent' process) will be the process id if the
copy. The copy is usually referred to as the 'child' process. The
value returned to the 'child' process will be zero.
All logical units open for writing are flushed before the fork to avoid
duplication of the contents of I/O buffers in the external file(s).
If the returned value is negative, it indicates an error and will be
the negation of the system error code. See perror(3F).
A corresponding exec routine has not been provided because there is no
satisfactory way to retain open logical units across the exec. How-
ever, the usual function of fork/exec can be performed using sys-
fork(2), wait(3F), kill(3F), system(3F), perror(3F)
4th Berkeley Distribution 13 June 1983 FORK(3F)