| Hello,
| I would like my program to know where it has been installed, in
| particular, the location of $datadir. Looks like a natural way to do
| it is to have a #define in config.h, like this:
|
| /*
| * myprog data directory
| */
| #define MYPROG_DATA_DIR "/usr/local/share/myprog"
|
| I tried the following in configure.in:
|
| AC_DEFINE_UNQUOTED(MYPROG_DATA_DIR,$datadir,[myprog data directory])
|
| but it doesn't work ($prefix/share is inserted and not expanded). I
| would appreciate it if someone could tell me how to do this properly.
|
| Thanks in advance.
See the documentation.
Installation Directory Variables
--------------------------------
[...]
Most of these variables have values that rely on `prefix' or
`exec_prefix'. It is deliberate that the directory output variables
keep them unexpanded: typically `@datadir@' will be replaced by
`${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 corresponding to the make-specified prefix.
`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 `${prefix}/share' to depend upon the current
value of `prefix'.
A corollary is that you should not use these variables except in
Makefiles. For instance, instead of trying to evaluate `datadir' in
`configure' and hardcoding it in Makefiles using e.g.
`AC_DEFINE_UNQUOTED(DATADIR, "$datadir")', you should add
`-DDATADIR="$(datadir)"' to your `CPPFLAGS'.
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.
