Rob van der Leek <[EMAIL PROTECTED]> writes:
> Hi list,
>
> I want to define a path to a configuration file in `config.h`, therefore
> I call AC_DEFINE_UNQUOTED(CONFIG_FILE, $prefix/etc/config.xml, [Path to
> config file])
> The problem is that $prefix defaults to NONE when no --prefix flag is
> given at the command line, which forces me to test for this situation
> and set $prefix to '/usr/local' by hand.
>
> Am I missing a point here? Any comments are welcome.
Installation Directory Variables
--------------------------------
The following variables specify the directories where the package
will be installed, see *Note Variables for Installation Directories:
(standards)Directory Variables, for more information. See the end of
this section for details on when and how to use these variables.
- Variable: bindir
The directory for installing executables that users run.
- Variable: datadir
The directory for installing read-only architecture-independent
data.
- Variable: exec_prefix
The installation prefix for architecture-dependent files. By
default it's the same as PREFIX. You should avoid installing
anything directly to EXEC_PREFIX. However, the default value for
directories containing architecture-dependent files should be
relative to EXEC_PREFIX.
- Variable: includedir
The directory for installing C header files.
- Variable: infodir
The directory for installing documentation in Info format.
- Variable: libdir
The directory for installing object code libraries.
- Variable: libexecdir
The directory for installing executables that other programs run.
- Variable: localstatedir
The directory for installing modifiable single-machine data.
- Variable: mandir
The top-level directory for installing documentation in man format.
- Variable: oldincludedir
The directory for installing C header files for non-gcc compilers.
- Variable: prefix
The common installation prefix for all files. If EXEC_PREFIX is
defined to a different value, PREFIX is used only for
architecture-independent files.
- Variable: sbindir
The directory for installing executables that system
administrators run.
- Variable: sharedstatedir
The directory for installing modifiable architecture-independent
data.
- Variable: sysconfdir
The directory for installing read-only single-machine data.
Most of these variables have values that rely on `prefix' or
`exec_prefix'. It is on purpose that the directory output variables
keep them unexpanded: typically `@datadir@' will be replaced by
`${prefix}/share', not `/usr/local/share'.
This behavior is mandated by the GNU coding standards, so that when
the user runs:
`make'
she can still specify a different prefix from the one specified to
`configure', in which case, if needed, the package shall hard code
dependencies to her late desires.
`make install'
she can specify a different installation location, in which case
the package _must_ still depend on the location which was compiled
in (i.e., never recompile when `make install' is run). This is an
extremely important feature, as many people may decide to install
all the files of a package grouped together, and then install
links from the final locations to there.
In order to support these features, it is essential that `datadir'
remains being defined as `${prefix}/share' to depend upon the current
value of `prefix'.
A corollary is that you should not use these variables but in
Makefiles. For instance, instead of trying to evaluate `datadir' in
`configure' and hardcoding it in Makefiles using e.g.
`AC_DEFINE_UNQUOTED(DATADIR, "$datadir")', you should add
`-DDATADIR="$(datadir)"' to your `CFLAGS'.
Similarly you should not rely on `AC_OUTPUT_FILES' to replace
`datadir' and friends in your shell scripts and other files, rather let
`make' manage their replacement. For instance Autoconf ships templates
of its shell scripts ending with `.sh', and uses this Makefile snippet:
.sh:
rm -f $@ $@.tmp
sed 's,@datadir\@,$(pkgdatadir),g' $< >$@.tmp
chmod +x $@.tmp
mv $@.tmp $@
Three things are noteworthy:
`@datadir\@'
The backslash prevents `configure' from replacing `@datadir@' in
the sed expression itself.
`$(pkgdatadir)'
Don't use `@pkgdatadir@'! Use the matching makefile variable
instead.
`,'
Don't use `/' in the sed expression(s) since most probably the
variables you use, such as `$(pkgdatadir)', will contain some.
