PXFFORK(3F) Last changed: 1-6-98
NAMEPXFFORK - Creates a process
SYNOPSIS
SUBROUTINE PXFFORK (ipid, ierror)
INTEGER ipid, ierror
IMPLEMENTATION
UNICOS, UNICOS/mk, and IRIX systems
DESCRIPTION
On IRIX systems, this routine is in libfortran.so which is linked by
default when compiling programs with the MIPSpro 7 Fortran 90 compiler
or when compiling programs with the -craylibs option to the MIPSpro
7.2 F77 compiler.
The PXFFORK routine uses the fork(2) system call to create a new
process. The child process is the same as the parent process except
for the following:
* The child process has a unique, currently unused process ID.
* The child process has a different parent process ID. The child
process's process ID is the parent process, or calling process, ID.
* 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 process.
* Process locks are not inherited by the child process (see plock(2)).
* The utime, stime, cutime, and cstime of the child process are set to
0. The time left until an alarm clock signal is reset to 0.
* All semadj values are cleared (see semop(2)).
* The parent's set of pending signals are not inherited by the child.
UNICOS and UNICOS/mk systems only:
* Record locks set by the parent process are not inherited by the
child process (see fcntl(2) and lockf(3C)).
* In a multitasking group, only the process that executed the fork
system call is copied.
* Each attached shared memory segment is attached and the value of
shm_nattch in the data structure associated with the shared memory
segment is incremented by 1.
IRIX systems only:
* File locks previously set by the parent are not inherited by the
child (see fcntl(2)).
* Page locks are not inherited (see mpin(2) on IRIX systems).
* The time left until an itimer signal is reset to 0.
* The child will not inherit the ability to make graphics calls. The
child process may receive a segmentation fault upon attempting to
make a graphics call, unless it initializes itself as a graphics
process via winopen() or ginit(). Currently, if the parent is a
graphics process, the child's attempt to become a graphics process
will fail.
* The share mask is set to 0 (see sproc(2)).
When using the CF90 compiler or MIPSpro 7 Fortran 90 compiler on
UNICOS, UNICOS/mk, or IRIX systems, all arguments must be of default
kind unless documented otherwise. On UNICOS and UNICOS/mk, default
kind is KIND=8 for integer, real, complex, and logical arguments; on
IRIX, the default kind is KIND=4.
The following is a list of arguments for this routine:
ipid An output integer variable. ipid will be zero for the child
process and the process ID of the child for the parent
process.
ierror An output integer variable that contains zero if PXFFORK was
successful or nonzero if PXFFORK was not successful.
The PXFFORK routine may return any of the following error values:
EAGAIN If the system-imposed limit on the total number of processes
under execution in the whole system (NPROC) is exceeded or
if the system-imposed limit on the total number of processes
under execution by one user (CHILD_MAX) is exceeded.
UNICOS and UNICOS/mk systems only:
EBUSY If you attempt to enable accounting when it is already
enabled, or if you issue a restart(2) attempt when another
job or process in the system is using the jid or any pid
associated with the job (or process) to be restarted.
EINTR If an asynchronous signal (such as interrupt or quit), which
you have elected to catch, occurred during a fork system
call. When execution resumed after processing the signal,
the interrupted system call returned this error condition.
EMEMLIM If more memory space was requested than is allowed for the
processes attached to this lnode. The maximum value is set
by the -c option of the shradmin(8) command. This error
appears only on systems running the fair-share scheduler.
ENOEXEC If a request was made to execute a file that, although it
has the appropriate permissions, does not start with a valid
magic number (see a.out(5)).
ENOMEM If during an exec(2) or sbreak(2) system call, a program
requested more space than the system could supply. This is
not a temporary condition; the maximum space specification
is a system parameter.
EPROCLIM If more processes were requested than are allowed for this
lnode. The maximum value is set by the -p option of the
shradmin(8) command. This error appears only on systems
running the fair-share scheduler.
IRIX systems only:
EAGAIN If the amount of system memory required is temorarily
unavailable.
ENOSPC If the caller is a member of a share group and the total
number of share group members plus child processes exceeds
the maximum number of users specified by the usconfig(3P)
command (8 by default). Any changes made with usconfig (3P)
must be done Ibeforethe first sproc is formed.
ENOLCK There are not enough file locks in the system.
EXAMPLES
program pxftest
integer ipid, ierror
CALL PXFFORK(ipid, ierror)
if (ipid .eq. 0) then
print *,'child'
else
print *,'parent'
endif
end
SEE ALSOexec(2), fcntl(2), fork(2), plock(2), restart(2), semop(2), sproc(2),
ssbreak(2)shradmin(8)
Application Programmer's Library Reference Manual, publication SR-
2165, for the printed version of this man page.
