[PATCH] qemu-nbd: Document benefit of --pid-file

[Eric Blake]

One benefit of --pid-file is that it is easier to probe the file
system to see if a pid file has been created than it is to probe if a
socket is available for connection. Document that this is an
intentional feature.

Signed-off-by: Eric Blake <address@hidden>
---
 qemu-nbd.texi | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/qemu-nbd.texi b/qemu-nbd.texi
index 7f55657722bd..d495bbe8a0ed 100644
--- a/qemu-nbd.texi
+++ b/qemu-nbd.texi
@@ -118,7 +118,8 @@ in list mode.
 @item --fork
 Fork off the server process and exit the parent once the server is running.
 @item --pid-file=PATH
-Store the server's process ID in the given file.
+Store the server's process ID in the given file.  The pid file is not
+created until after the server socket is open.
 @item --tls-authz=ID
 Specify the ID of a qauthz object previously created with the
 --object option. This will be used to authorize connecting users
-- 
2.21.0