2.3 The Build Script

The first step in compiling sendmail is to establish an object directory and a Makefile that is appropriate to your machine architecture and operating system. You do this by running the Build script in the sendmail source directory:^[3]

^[3] This same Build script is also used to build all the support programs, such as mailstats, smrsh(1), and mail.local(1). We describe support programs in Chapter 5.

% cd sendmail 
% ./Build -n 
Configuration: pfx=, os=SunOS, rel=4.1.4, rbase=4, rroot=4.1, arch=sun4, sfx=
Using M4=/usr/5bin/m4
Creating ../obj.SunOS.4.1.4.sun4/sendmail using ../devtools/OS/SunOS
   many more lines here
%

Here, Build found that our machine was a sun4, running the SunOS 4.1.4 release of Unix. Build then created the working directory ../obj.SunOS.4.1.4.sun4, set up symbolic links to all the source files in that directory, and finally generated a Makefile there.

The Build program understands several command-line switches that can be used to modify its behavior (see Table 2-2). Any switch or other command-line argument that is not in that table is carried through and passed as is to the make(1) program. For example, specifying the -n switch to Build (in the earlier example) caused Build to pass that switch to make(1), thereby preventing make(1) from actually building sendmail.

Table 2-2. Build command-line switches

Switch	§	Description
-A	-A	Show the architecture for the build.
-c	-c	Clean out an existing object tree.
-E	-E	Pass environment variables to build.
-f	-f	Use site file in alternative directory.
-I	-I	Add additional include directories.
-L	-L	Add additional library directories.
-m	-m	Show but don't create the directory.
-M	-M	Show the name of the object directory.
-O	-O	Specify the path of the object directory.
-Q	-Q	Set prefix for the object directory and Build m4 configuration file.
-S	-S	Skip system-specific configuration.