14.3 The dist Hook

Occasionally it is useful to be able to change the distribution before it is packaged up. If the dist-hook rule exists, it is run after the distribution directory is filled, but before the actual distribution archives are created. One way to use this is for removing unnecessary files that get recursively included by specifying a directory in EXTRA_DIST:

EXTRA_DIST = doc
dist-hook:
        rm -rf `find $(distdir)/doc -type d -name .svn`

Note that the dist-hook recipe shouldn’t assume that the regular files in the distribution directory are writable; this might not be the case if one is packaging from a read-only source tree, or when a make distcheck is being done. For similar reasons, the recipe shouldn’t assume that the subdirectories put into the distribution directory as effect of having them listed in EXTRA_DIST are writable. So, if the dist-hook recipe wants to modify the content of an existing file (or EXTRA_DIST subdirectory) in the distribution directory, it should explicitly to make it writable first:

EXTRA_DIST = README doc
dist-hook:
        chmod u+w $(distdir)/README $(distdir)/doc
        echo "Distribution date: `date`" >> README
        rm -f $(distdir)/doc/HACKING

Two variables that come handy when writing dist-hook rules are ‘$(distdir)’ and ‘$(top_distdir)’.

‘$(distdir)’ points to the directory where the dist rule will copy files from the current directory before creating the tarball. If you are at the top-level directory, then ‘distdir = $(PACKAGE)-$(VERSION)’. When used from subdirectory named foo/, then ‘distdir = ../$(PACKAGE)-$(VERSION)/foo’. ‘$(distdir)’ can be a relative or absolute path, do not assume any form.

‘$(top_distdir)’ always points to the root directory of the distributed tree. At the top-level it’s equal to ‘$(distdir)’. In the foo/ subdirectory ‘top_distdir = ../$(PACKAGE)-$(VERSION)’. ‘$(top_distdir)’ too can be a relative or absolute path.

Note that when packages are nested using AC_CONFIG_SUBDIRS (see Nesting Packages), then ‘$(distdir)’ and ‘$(top_distdir)’ are relative to the package where ‘make dist’ was run, not to any sub-packages involved.