* Help text for all (non-script) programs, so no more:

$ nix-instantiate --help
error: unknown flag `--help`
Try `nix-instantiate --help' for more information.

:-)

src/nix-hash/Makefile.am

@@ -4,5 +4,10 @@ nix_hash_SOURCES = nix-hash.cc
 nix_hash_LDADD = ../libmain/libmain.a ../libstore/libstore.a ../libutil/libutil.a \
  ../boost/format/libformat.a -L../../externals/inst/lib -ldb_cxx -lATerm
 
+nix-hash.o: help.txt.hh
+
+%.txt.hh: %.txt
+	../bin2c/bin2c helpText < $< > $@ || (rm $@ && exit 1)
+
 AM_CXXFLAGS = \
  -I.. -I../../externals/inst/include -I../libutil -I../libstore -I../libmain

src/nix-hash/help.txt

@@ -0,0 +1,6 @@
+nix-hash [OPTIONS...] [FILES...]
+
+`nix-hash computes and prints cryptographic hashes for the specified
+files.
+
+  --flat: compute hash of regular file contents, not metadata

src/nix-hash/nix-hash.cc

@@ -2,6 +2,13 @@
 
 #include "hash.hh"
 #include "shared.hh"
+#include "help.txt.hh"
+
+
+void printHelp()
+{
+    cout << string((char *) helpText, sizeof helpText);
+}
 
 
 void run(Strings args)