APPENDDEF( )
Append to an existing define Build directive
The APPENDDEF( ) m4 directive
allows you to append new information to information
that was previously defined. To illustrate, consider
that the locations of your #include
files are sometimes preset in
the appropriate devtools/OS
directory. For OS/UXPDS.V10, for example, the
default is:
-I/usr/include -I/usr/ucbinclude
You can use this APPENDDEF( ) directive to add another directory to this list, without erasing what is already there:
APPENDDEF(`confINCDIRS', `-I/usr/local/include/db')
This causes the new directory to be appended to the declaration in the previous example:
-I/usr/include -I/usr/ucbinclude -I/usr/local/include/db
Even when you are not sure whether a macro has been given a value by default, you can safely use this APPENDDEF( ) directive because no harm is caused by appending to an empty definition. See also PREPENDDEF( ) in PREPENDDEF( ) on page 102.
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