FORK(2)                  DOMAIN/IX SYS5                   FORK(2)



NAME
     fork - create a new process

USAGE
     int fork()

DESCRIPTION
     Fork causes a new process to be created.  The new, or child,
     process is an exact copy of the calling, or parent, process.
     The child process inherits the following attributes from the
     parent process:

          environment
          close-on-exec flag (see exec(2))
          signal handling settings (i.e., SIG_DFL, SIG_IGN, func-
          tion address)
          set-user-ID mode bit
          set-group-ID mode bit
          nice value (see nice(2))
          all attached shared memory segments (see shmop(2))
          process group ID
          tty group ID (see exit(2) and signal(2))
          time left until an alarm clock signal (see alarm(2))
          current working directory
          root directory
          file mode creation mask (see umask(2))

     The child process differs from the parent process in the
     following ways:

          The child process has a unique process ID.

          The child process has a different parent process ID
          (i.e., the child's parent is not the parent's parent).

          The child process has its own copy of the parent's file
          descriptors.  Each of the child's file descriptors
          shares a common file pointer with the corresponding
          file descriptor of the parent.

          All semadj values are cleared (see semop(2)).

          Process locks, text locks and data locks are not inher-
          ited by the child (see plock(2)).

          The child process's utime, stime, cutime, and cstime
          are set to zero.  The time left until an alarm clock
          signal is reset to zero.





Printed 12/4/86                                            FORK-1

FORK(2)                  DOMAIN/IX SYS5                   FORK(2)



NOTES
     On DOMAIN systems, fork may produce unexpected or undesired
     results when called from an mbx server process, or form a
     process using gpr or gpio.

RETURN VALUE
     Upon successful completion, fork returns a value of zero to
     the child process and returns the process ID of the child
     process to the parent process.  Otherwise, it returns -1 to
     the parent process, no child process is created, and errno
     is set to indicate the error.

ERRORS
     Fork fails and no child process is created if one or more of
     the following is true:

     [EAGAIN]  The system-imposed limit on the total number of
               processes under execution would be exceeded.

     [EAGAIN]  The system-imposed limit on the total number of
               processes under execution by a single user would
               be exceeded.

RELATED INFORMATION
     exec(2), nice(2), plock(2), semop(2), shmop(2), signal(2),
     times(2), umask(2), wait(2)



























FORK-2                                            Printed 12/4/86