get: Add --batch and --json options.

doc/git-annex-get.mdwn

@@ -45,6 +45,11 @@ or transferring them from some kind of key-value store.
   as git-annex does not know the associated file, and the associated file
   may not even be in the current git working directory.
 
+* file matching options
+ 
+  The [[git-annex-matching-options]](1)
+  can be used to specify files to get.
+
 * `--all`
 
   Rather than specifying a filename or path to get, this option can be
@@ -60,10 +65,23 @@ or transferring them from some kind of key-value store.
 
   Use this option to get a specified key.
 
-* file matching options
- 
-  The [[git-annex-matching-options]](1)
-  can be used to specify files to get.
+* `--batch`
+
+  Enables batch mode, in which lines containing names of files to get
+  are read from stdin.
+
+  As each specified file is processed, the usual progress output is
+  displayed. If the specified file's content is already present, or
+  it is not an annexed file, a blank line is output in response instead.
+
+  Since the usual progress output while getting a file is verbose and not
+  machine-parseable, you may want to use --json in combination with
+  --batch.
+
+* `--json`
+
+  Enable JSON output. This is intended to be parsed by programs that use
+  git-annex. Each line of output is a JSON object.
 
 # SEE ALSO
 

doc/todo/get_--batch.mdwn

@@ -1,3 +1,7 @@
 It seems that it would be tremendously useful, see e.g. our [datalad install](https://github.com/datalad/datalad/issues/553)
 
-[[!meta author =yoh]]
+[[!meta author=yoh]]
+
+> [[done]] although the output while getting a file is not
+> machine-parseable. So, I made --json also work for get, but enabling
+> json output disables any progress display. --[[Joey]]