add metadata command to get/set metadata

Adds metadata log, and command.

Note that unsetting field values seems to currently be broken.
And in general this has had all of 2 minutes worth of testing.

This commit was sponsored by Julien Lefrique.

1 files changed, 17 insertions, 0 deletions

diff --git a/doc/git-annex.mdwn b/doc/git-annex.mdwn
index 4e672f608..17d78c555 100644
--- a/doc/git-annex.mdwn
+++ b/doc/git-annex.mdwn
@@ -695,6 +695,23 @@ subdirectories).
 
 # UTILITY COMMANDS
 
+* `metadata file [field=value field+=value field-=value ...]`
+
+  Each file can have any number of metadata fields attached to it,
+  which each in turn have any number of values. This sets metadata
+  for a file, or if run without any values, shows its current metadata.
+
+  To set a field's value, removing any old value(s), use field=value.
+
+  To add an additional value, use field+=value.
+
+  To remove a value, use field-=value.
+
+  For example, to set some tags on a file:
+
+        	git annex metadata annexscreencast.ogv tag+=video tag+=screencast
+
+
 * `migrate [path ...]`
 
   Changes the specified annexed files to use the default key-value backend