2.2.7 Two-Part Installation

In our last example (see section Parallel Build Trees (a.k.a. VPATH Builds)), a source tree was shared by two hosts, but compilation and installation were done separately on each host.

The GNU Build System also supports networked setups where part of the installed files should be shared amongst multiple hosts. It does so by distinguishing architecture-dependent files from architecture-independent files, and providing two ‘Makefile’ targets to install each of these classes of files.

These targets are install-exec for architecture-dependent files and install-data for architecture-independent files. The command we used up to now, make install, can be thought of as a shorthand for make install-exec install-data.

From the GNU Build System point of view, the distinction between architecture-dependent files and architecture-independent files is based exclusively on the directory variable used to specify their installation destination. In the list of directory variables we provided earlier (see section Standard Directory Variables), all the variables based on exec-prefix designate architecture-dependent directories whose files will be installed by make install-exec. The others designate architecture-independent directories and will serve files installed by make install-data. See section The Two Parts of Install, for more details.

Here is how we could revisit our two-host installation example, assuming that (1) we want to install the package directly in ‘/usr’, and (2) the directory ‘/usr/share’ is shared by the two hosts.

On the first host we would run

[HOST1] ~ % mkdir /tmp/amh && cd /tmp/amh
[HOST1] /tmp/amh % /nfs/src/amhello-1.0/configure --prefix /usr
...
[HOST1] /tmp/amh % make && sudo make install
...

On the second host, however, we need only install the architecture-specific files.

[HOST2] ~ % mkdir /tmp/amh && cd /tmp/amh
[HOST2] /tmp/amh % /nfs/src/amhello-1.0/configure --prefix /usr
...
[HOST2] /tmp/amh % make && sudo make install-exec
...

In packages that have installation checks, it would make sense to run make installcheck (see section Basic Installation) to verify that the package works correctly despite the apparent partial installation.

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