12. What Gets Installed

Naturally, Automake handles the details of actually installing your program once it has been built. All files named by the various primaries are automatically installed in the appropriate places when the user runs `make install'.

12.1 Basics of Installation

A file named in a primary is installed by copying the built file into the appropriate directory. The base name of the file is used when installing.

bin_PROGRAMS = hello subdir/goodbye

In this example, both `hello' and `goodbye' will be installed in `$(bindir)'.

Sometimes it is useful to avoid the basename step at install time. For instance, you might have a number of header files in subdirectories of the source tree that are laid out precisely how you want to install them. In this situation you can use the nobase_ prefix to suppress the base name step. For example:

nobase_include_HEADERS = stdio.h sys/types.h

will install `stdio.h' in `$(includedir)' and `types.h' in `$(includedir)/sys'.

For most file types, Automake will install multiple files at once, while avoiding command line length issues (see section Staying below the command line length limit). Since some install programs will not install the same file twice in one invocation, you may need to ensure that file lists are unique within one variable such as `nobase_include_HEADERS' above.

You should not rely on the order in which files listed in one variable are installed. Likewise, to cater for parallel make, you should not rely on any particular file installation order even among different file types (library dependencies are an exception here).

12.2 The Two Parts of Install

Automake generates separate install-data and install-exec rules, in case the installer is installing on multiple machines that share directory structure--these targets allow the machine-independent parts to be installed only once. install-exec installs platform-dependent files, and install-data installs platform-independent files. The install target depends on both of these targets. While Automake tries to automatically segregate objects into the correct category, the `Makefile.am' author is, in the end, responsible for making sure this is done correctly.

Variables using the standard directory prefixes `data', `info', `man', `include', `oldinclude', `pkgdata', or `pkginclude' are installed by install-data.

Variables using the standard directory prefixes `bin', `sbin', `libexec', `sysconf', `localstate', `lib', or `pkglib' are installed by install-exec.

For instance, data_DATA files are installed by install-data, while bin_PROGRAMS files are installed by install-exec.

Any variable using a user-defined directory prefix with `exec' in the name (e.g., myexecbin_PROGRAMS) is installed by install-exec. All other user-defined prefixes are installed by install-data.

12.3 Extending Installation

It is possible to extend this mechanism by defining an install-exec-local or install-data-local rule. If these rules exist, they will be run at `make install' time. These rules can do almost anything; care is required.

Automake also supports two install hooks, install-exec-hook and install-data-hook. These hooks are run after all other install rules of the appropriate type, exec or data, have completed. So, for instance, it is possible to perform post-installation modifications using an install hook. See section Extending Automake Rules, for some examples.

12.4 Staged Installs

Automake generates support for the DESTDIR variable in all install rules. DESTDIR is used during the `make install' step to relocate install objects into a staging area. Each object and path is prefixed with the value of DESTDIR before being copied into the install area. Here is an example of typical DESTDIR usage:

mkdir /tmp/staging &&
make DESTDIR=/tmp/staging install

The mkdir command avoids a security problem if the attacker creates a symbolic link from `/tmp/staging' to a victim area; then make places install objects in a directory tree built under `/tmp/staging'. If `/gnu/bin/foo' and `/gnu/share/aclocal/foo.m4' are to be installed, the above command would install `/tmp/staging/gnu/bin/foo' and `/tmp/staging/gnu/share/aclocal/foo.m4'.

This feature is commonly used to build install images and packages (see section Building Binary Packages Using DESTDIR).

Support for DESTDIR is implemented by coding it directly into the install rules. If your `Makefile.am' uses a local install rule (e.g., install-exec-local) or an install hook, then you must write that code to respect DESTDIR.

See (standards)Makefile Conventions section `Makefile Conventions' in The GNU Coding Standards, for another usage example.

12.5 Install Rules for the User

Automake also generates rules for targets uninstall, installdirs, and install-strip.

Automake supports uninstall-local and uninstall-hook. There is no notion of separate uninstalls for "exec" and "data", as these features would not provide additional functionality.

Note that uninstall is not meant as a replacement for a real packaging tool.

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