The -I switch is used to list include-file directories on the command-line. When used with -L (-L), for example, it can select an experimental version of BIND:

% ./Build -I/src/bind/8.8.1x5/include -L/src/bind/8.8.1x5/lib

The value specified with this -I switch is appended to whatever values are specified in your m4 build file with confINCDIRS (confINCDIRS), and to whatever values might be preset as defaults in your devtools/OS file. The final, assembled value is made a part of your configuration file, and is also made the value of the INCDIRS= directive in your Makefile.

Multiple -I switches can be used to specify a series of include directories. For example:

% ./Build -I/usr/local/include -I/usr/tools/include

In general, include-file directories should be listed with the confINCDIRS m4 directive (confINCDIRS) in your m4 build file, instead of on the command line.