Earliest reference to /dev/null I can find is in v4 sh(1) and nulldev in

nsys/ken/subr.c
via TUHS archive
https://minnie.tuhs.org/cgi-bin/utree.pl?file=V4

MFC after:	5 days

diff --git a/share/man/man4/null.4 b/share/man/man4/null.4
index 067c2d8e7f39e6378e130fe3df2f4b73f2ac7dd6..fdbca2b102fe09ab58d60d1b479781947b2cf433 100644 (file)
--- a/share/man/man4/null.4
+++ b/share/man/man4/null.4
@@ -28,7 +28,7 @@
 .\"    @(#)null.4      8.1 (Berkeley) 6/5/93
 .\" $FreeBSD$
 .\"
-.Dd June 5, 1993
+.Dd August 30, 2019
 .Dt NULL 4
 .Os
 .Sh NAME
@@ -54,4 +54,4 @@ device is always zero.
 A
 .Nm
 device appeared in
-.At v7 .
+.At v4 .