mingw: document the standard handle redirection

This feature has been in Git for Windows since v2.11.0(2), as an
experimental option. Now it is considered mature, and it is high time to
document it properly.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/git.txt b/Documentation/git.txt
index 7a1d629ca068059d274da66728eb7f886b43081d..463b0eb0f5c3c8e694a509d3e06aee29056f970d 100644 (file)
--- a/Documentation/git.txt
+++ b/Documentation/git.txt
@@ -709,6 +709,24 @@ of clones and fetches.
        the background which do not want to cause lock contention with
        other operations on the repository.  Defaults to `1`.
 
+`GIT_REDIRECT_STDIN`::
+`GIT_REDIRECT_STDOUT`::
+`GIT_REDIRECT_STDERR`::
+       Windows-only: allow redirecting the standard input/output/error
+       handles to paths specified by the environment variables. This is
+       particularly useful in multi-threaded applications where the
+       canonical way to pass standard handles via `CreateProcess()` is
+       not an option because it would require the handles to be marked
+       inheritable (and consequently *every* spawned process would
+       inherit them, possibly blocking regular Git operations). The
+       primary intended use case is to use named pipes for communication
+       (e.g. `\\.\pipe\my-git-stdin-123`).
++
+Two special values are supported: `off` will simply close the
+corresponding standard handle, and if `GIT_REDIRECT_STDERR` is
+`2>&1`, standard error will be redirected to the same handle as
+standard output.
+
 Discussion[[Discussion]]
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