msgctl.2: Add description of 'msg_cbytes' field

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

diff --git a/man2/msgctl.2 b/man2/msgctl.2
index a735ce9c4d6113d9632255eed622ec5feda525e5..87d66052614279ccadb2edbde740ecbb033bc6c8 100644 (file)
--- a/man2/msgctl.2
+++ b/man2/msgctl.2
@@ -103,6 +103,10 @@ Time of creation of queue or time of last
 .BR IPC_SET
 operation.
 .TP
+.I msg_cbytes
+Number of bytes in all messages currently on the message queue.
+This is a nonstandard Linux extension that is not specified in POSIX.
+.TP
 .I msg_qnum
 Number of messages currently on the message queue.
 .TP