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ICAM Virtual Machine ® Virtual Machine Reference, Model Customization
The Macro Language, Text File I/O from a Macro
Macro matching is always automatically turned back on when the current macro is exited.
Startup, shutdown and event macros are always invoked even if macro matching is turned OFF.
Outputting the Matched Record (OUTPUT)
The OUTPUT command instructs the macro processor to execute the actions associated with the
current event. The syntax of the OUTPUT command is simply:
OUTPUT
The OUTPUT command must be coded in Model Event macros only; do not code OUTPUT in a
startup or shutdown macro. If the OUTPUT command is not encountered in an event macro, then
the built-in processing for that event will not occur. This gives you the opportunity in an event
macro to insert your own processing before, after, or even in place of the built-in processing.
Note that the OUTPUT command is also used with CERUN and GENER User-Defined macros to
indicate the point in the user-defined macro where the matched command should be processed.
4.4.1.4 Text File I/O from a Macro
The macro language provides the ability to read from and write to external text files. These files
are connected to and disconnected from the macro processor using OPEN and CLOSE commands.
Input and output to external files is done using the READ and WRITE commands.
When a file is opened, it must be assigned a “unit” number. This is a number from 20 through 29
that will then be used in subsequent READ, WRITE and CLOSE statements to identify the
particular file opened. This enables multiple files to be simultaneously opened for processing.
If an error occurs during text file I/O, the error return code will be stored in the $ERRNO macro
system variable. Macros must test for I/O errors and act accordingly since a diagnostic will not
be output to indicate an I/O failure.
Opening a Text File (OPEN)
The OPEN command opens a text file with a given name on a given unit. The file name is
optional if the unit is pre-connected. If FRONT is specified, the unit is rewound. If REAR is
specified, the unit is positioned at the end-of-file. FRONT is the default. The OPEN command
has the following syntax:
OPEN/ unit
� FRONT
,
�
�
[ , filename ]
� REAR �� Two special file names are predefined to permit input and output to the console; they are STDIN
and STDOUT.
Closing a Text File (CLOSE)
The CLOSE command closes a text file. It has the following syntax:
CLOSE/
unit
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