When ‘--help’ is given, just run ‘man’ to show the manual page

I.e. do what git does.  I'm too lazy to keep the builtin help text up
to date :-)

Also add ‘--help’ to various commands that lacked it
(e.g. nix-collect-garbage).

1 files changed, 1 insertions, 2 deletions

diff --git a/src/nix-hash/nix-hash.cc b/src/nix-hash/nix-hash.cc
index 5b35ccd9dae3..af3dda4ad7b8 100644
--- a/src/nix-hash/nix-hash.cc
+++ b/src/nix-hash/nix-hash.cc
@@ -1,6 +1,5 @@
 #include "hash.hh"
 #include "shared.hh"
-#include "help.txt.hh"
 
 #include <iostream>
 
@@ -10,7 +9,7 @@ using namespace nix;
 
 void printHelp()
 {
-    std::cout << string((char *) helpText);
+    showManPage("nix-hash");
 }