XL Fortran Enterprise Edition for AIX : User's Guide - IBM

v
Files on sequential-access devices (such as pipes, terminals, sockets, and tape
drives)
To avoid the possibility of damaging the file, keep the following points in
mind:
v The second and subsequent OPEN statements for the same file can only be
for reading.
v If you initially opened the file for both input and output purposes
(ACTION=’READWRITE’), the unit connected to the file by the first OPEN
becomes read-only (ACCESS=’READ’) when the second unit is connected.
You must close all of the units that are connected to the file and reopen the
first unit to restore write access to it.
v Two files are considered to be the same file if they share the same device
and i-node numbers. Thus, linked files are considered to be the same file.
multconnio={tty | nulldev | combined | no }
Enables you to connect a device to more than one logical unit. You can then
write to, or read from, more than one logical unit that is attached to the same
device. The suboptions are as follows:
combined
Enables you to connect a combination of null and TTY devices to more
than one logical unit.
nulldev
Enables you to connect the null device to more than one logical unit.
tty Enables you to connect a TTY device to more than one logical unit.
Note: Using this option can produce unpredictable results.
In your program, you can now specify multiple OPEN statements that
contain different values for the UNIT parameters but the same value for
the FILE parameters. For example, if you have a symbolic link called
mytty that is linked to TTY device /dev/tty, you can run the following
program when you specify the multconnio=tty option:
PROGRAM iotest
OPEN(UNIT=3, FILE=’mytty’, ACTION="WRITE")
OPEN(UNIT=7, FILE=’mytty’, ACTION="WRITE")
END PROGRAM iotest
Fortran preconnects units 0, 5, and 6 to the same TTY device. Normally,
you cannot use the OPEN statement to explicitly connect additional units
to the TTY device that is connected to units 0, 5, and 6. However, this is
possible if you specify the multconnio=tty option. For example, if units 0,
5, and 6 are preconnected to TTY device /dev/tty, you can run the
following program if you specify the multconnio=tty option:
PROGRAM iotest
! /dev/pts/2 is your current tty, as reported by the ’tty’ command.
! (This changes every time you login.)
CALL SETRTEOPTS (’multconnio=tty’)
OPEN (UNIT=3, FILE=’/dev/pts/2’)
WRITE (3, *) ’hello’ ! Display ’hello’ on your screen
END PROGRAM
namelist={new | old}
Determines whether the program uses the XL Fortran new or old (Version 1)
NAMELIST format for input and output. The Fortran 90 and Fortran 95
standards require the new format.
Editing, Compiling, Linking, and Running XL Fortran Programs 57