$GIT_COMMON_DIR: a new environment variable

diff --git a/Documentation/git-update-index.txt b/Documentation/git-update-index.txt
index 56626a005d4d2cb104a3ac8147d3d74b8d65b893..929869b0a0576b8c60a685af2fd6b236e3b4bf1d 100644 (file)
--- a/Documentation/git-update-index.txt
+++ b/Documentation/git-update-index.txt
@@ -161,6 +161,17 @@ may not support it yet.
        Only meaningful with `--stdin` or `--index-info`; paths are
        separated with NUL character instead of LF.
 
+--split-index::
+--no-split-index::
+       Enable or disable split index mode. If enabled, the index is
+       split into two files, $GIT_DIR/index and $GIT_DIR/sharedindex.<SHA-1>.
+       Changes are accumulated in $GIT_DIR/index while the shared
+       index file contains all index entries stays unchanged. If
+       split-index mode is already enabled and `--split-index` is
+       given again, all changes in $GIT_DIR/index are pushed back to
+       the shared index file. This mode is designed for very large
+       indexes that take a significant amount of time to read or write.
+
 \--::
        Do not interpret any more arguments as options.