Add 'guix archive'.

* guix/scripts/archive.scm, tests/guix-archive.sh: New files.
* Makefile.am (MODULES): Add 'archive.scm'.
  (SH_TESTS): Add 'guix-archive.sh'.
* doc/guix.texi (Invoking guix archive): New section.
* guix/scripts/build.scm: Export 'derivation-from-expression'.
* guix/scripts/package.scm: Export 'specification->package+output'.

tests/guix-archive.sh

@@ -0,0 +1,45 @@
+# GNU Guix --- Functional package management for GNU
+# Copyright © 2013 Ludovic Courtès <ludo@gnu.org>
+#
+# This file is part of GNU Guix.
+#
+# GNU Guix is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or (at
+# your option) any later version.
+#
+# GNU Guix is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+#
+# Test the 'guix archive' command-line utility.
+#
+
+guix archive --version
+
+archive="t-archive-$$"
+archive_alt="t-archive-alt-$$"
+rm -f "$archive" "$archive_alt"
+
+trap 'rm -f "$archive" "$archive_alt"' EXIT
+
+guix archive --export guile-bootstrap > "$archive"
+guix archive --export guile-bootstrap:out > "$archive_alt"
+cmp "$archive" "$archive_alt"
+
+guix archive --export							\
+    -e '(@ (gnu packages bootstrap) %bootstrap-guile)' > "$archive_alt"
+cmp "$archive" "$archive_alt"
+
+guix archive --export `guix build guile-bootstrap` > "$archive_alt"
+cmp "$archive" "$archive_alt"
+
+guix archive --import < "$archive" 2>&1 | grep "import.*guile-bootstrap"
+
+if guix archive something-that-does-not-exist
+then false; else true; fi