[PATCH] doc: document UNICORN_FD in manpage

[PATCH] doc: document UNICORN_FD in manpage

[Eric Wong]

Due to the prevalence of socket activation in modern init systems,
we shall document UNICORN_FD (previously an implementation detail)
in the manpage.
---
 Documentation/unicorn.1.txt | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/Documentation/unicorn.1.txt b/Documentation/unicorn.1.txt
index 376a6c6..b03962e 100644
--- a/Documentation/unicorn.1.txt
+++ b/Documentation/unicorn.1.txt
@@ -163,6 +163,13 @@ set in the old master process are inherited by the new master process.
 Unicorn only uses (and will overwrite) the UNICORN_FD environment
 variable internally when doing transparent upgrades.
 
+UNICORN_FD is a comma-delimited list of one or more file descriptors
+used to implement USR2 upgrades.  Init systems may bind listen sockets
+itself and spawn unicorn with UNICORN_FD set to the file descriptor
+numbers of the listen socket(s).  The unicorn CONFIG_FILE must still
+have the inherited listen socket parameters defined as in a normal
+startup, otherwise the socket will be closed.
+
 # SEE ALSO
 
 * unicorn_rails(1)
-- 
2.3.2.209.gd67f9d5