WIP: doc: Document DEFAULTCONFIGDIR in manpages

doc/Makefile.am

@@ -99,6 +99,7 @@ MAN2HTML = nroff -c -man |\
 	@if $(AM_V_P); then echo "Generating manpage $@..."; fi
 	@sed -e 's|@DATADIR@|$(datadir)|g' \
 	  -e 's|@CONFIGDIR@|$(configdir)|g' \
+	  -e 's|@DEFAULTCONFIGDIR@|$(defaultconfigdir)|g' \
 	  -e 's|@DOCDIR@|$(docdir)|g' \
 	  -e 's|@LIBDIR@|$(libdir)/sane|g' \
 	  -e 's|@BINDIR@|$(bindir)|g' \

doc/sane-u12.man

@@ -115,6 +115,9 @@ If there's no configuration file, the backend defaults to
 .I @CONFIGDIR@/u12.conf
 The backend configuration file
 .TP
+.I @DEFAULTCONFIGDIR@/u12.conf
+The backend default configuration file
+.TP
 .I @LIBDIR@/libsane\-u12.a
 The static library implementing this backend.
 .TP
@@ -130,8 +133,10 @@ contain the configuration file.  On *NIX systems, the directories are
 separated by a colon (`:'), under OS/2, they are separated by a
 semi-colon (`;').  If this variable is not set, the configuration file
 is searched in two default directories: first, the current working
-directory (".") and then in
-.IR @CONFIGDIR@ .
+directory ("."), then in
+.IR @CONFIGDIR@
+and then in
+.IR @DEFAULTCONFIGDIR@ .
 If the value of the
 environment variable ends with the directory separator character, then
 the default directories are searched after the explicitly specified
@@ -140,8 +145,9 @@ directories.  For example, setting
 to "/tmp/config:" would result in directories
 .IR tmp/config ,
 .IR . ,
+.IR @CONFIGDIR@ ,
 and
-.I @CONFIGDIR@
+.I @DEFAULTCONFIGDIR@
 being searched (in this order).
 .TP
 .B SANE_DEBUG_U12

doc/sane.man

@@ -716,7 +716,11 @@ that work is not duplicated.
 .SH "FILES"
 .TP
 .I @CONFIGDIR@/*.conf
-The backend configuration files.
+The backend configuration files (preferred to the default configuration
+files, if present).
+.TP
+.I @DEFAULTCONFIGDIR@/*.conf
+The backend default configuration files (read-only).
 .TP
 .I @LIBDIR@/libsane\-*.a
 The static libraries implementing the backends.

doc/scanimage.man

@@ -138,7 +138,8 @@ is used to include an ICC profile into a TIFF file.
 requests a (partial) list of devices that are available.  The
 list may not be complete since some devices may be available, but are not
 listed in any of the configuration files (which are typically stored
-in directory
+in
+.IR @DEFAULTCONFIGDIR@ and
 .IR @CONFIGDIR@ ).
 This is particularly the case when accessing scanners through the network.  If
 a device is not listed in a configuration file, the only way to access it is
@@ -478,8 +479,9 @@ filename
 The default device-name.
 .SH FILES
 .TP
-.I @CONFIGDIR@
-This directory holds various configuration files.  For details, please
+.IR @CONFIGDIR@ , \ \&\c
+.I @DEFAULTCONFIGDIR@
+These directories holds various configuration files.  For details, please
 refer to the manual pages listed below.
 .TP
 .I ~/.sane/pass