scripts: package: Add --install-from-file option.

* guix/scripts/package.scm (show-help): Add help text for --install-from-file
  option.
  (%options): Add --install-from-file option.
* tests/guix-package.sh: Test it.
* doc/guix.texi ("invoking guix package"): Document it.
* doc/package-hello.scm: New file.
* doc.am (EXTRA_DIST): Add it.

1 files changed, 18 insertions, 0 deletions

diff --git a/doc/package-hello.scm b/doc/package-hello.scm
new file mode 100644
index 00000000000..b3fcd4ff73b
--- /dev/null
+++ b/doc/package-hello.scm
@@ -0,0 +1,18 @@
+(use-modules (guix)
+             (guix build-system gnu)
+             (guix licenses))
+
+(package
+  (name "hello")
+  (version "2.8")
+  (source (origin
+            (method url-fetch)
+            (uri (string-append "mirror://gnu/hello/hello-" version
+                                ".tar.gz"))
+            (sha256
+             (base32 "0wqd8sjmxfskrflaxywc7gqw7sfawrfvdxd9skxawzfgyy0pzdz6"))))
+  (build-system gnu-build-system)
+  (synopsis "Hello, GNU world: An example GNU package")
+  (description "Guess what GNU Hello prints!")
+  (home-page "http://www.gnu.org/software/hello/")
+  (license gpl3+))