Add unvac to manual page.
You also need to do

	rm /sys/src/cmd/vac/*
	9fs sources
	cp /n/sources/contrib/rsc/nvac/* /sys/src/cmd/vac

☺

Reference: /n/sources/patch/applied/vac
Date: Sat Jun 14 20:27:31 CES 2008
Signed-off-by: rsc@swtch.com

--- /sys/man/1/vac	Sat Jun 14 20:26:59 2008
+++ /sys/man/1/vac	Sat Jun 14 20:26:59 2008
@@ -1,6 +1,6 @@
 .TH VAC 1
 .SH NAME
-vac \- create a vac archive on Venti
+vac, unvac \- create, extract a vac archive on Venti
 .SH SYNOPSIS
 .B vac
 [
@@ -25,6 +25,18 @@
 .I host
 ]
 .I file ...
+.PP
+.B unvac
+[
+.B -Tctv
+] [
+.B -h
+.I host
+]
+.I vacfile
+[
+.I file ...
+]
 .SH DESCRIPTION
 .I Vac
 creates an archival copy of Plan 9 file trees on Venti. It can be used
@@ -123,6 +135,32 @@
 .B -v
 Produce more verbose output on standard error, including the name of the files added to the archive
 and the vac archives that are expanded and merged.
+.PP
+.I Unvac
+lists or extracts files stored in the vac archive
+.IR vacfile ,
+which can be either a vac archive string in the format
+given above or the name of a file containing one.
+If
+.I file
+arguments are given, only those files or directories
+will be extracted.
+The options are:
+.TP
+.B -T
+Set the modification time on extracted files
+to the time listed in the archive.
+.TP
+.B -c
+Write extracted files to standard output instead of creating a file.
+.TP
+.B -t
+Print a list of the files to standard output rather than extracting them.
+.TP
+.B -v
+If extracting files, print the name of each file and directory
+to standard error.
+If listing files, print metadata in addition to the names.
 .SH SOURCE
 .B /sys/src/cmd/vac
 .SH "SEE ALSO"