upstream: support a prefix of '@' to suppress echo of sftp batch

commands; bz#2926; ok dtucker@

OpenBSD-Commit-ID: 9d635636bc84aeae796467e059f7634de990a79d
diff --git a/sftp.1 b/sftp.1
index 50e2fef..7140bc1 100644
--- a/sftp.1
+++ b/sftp.1
@@ -1,4 +1,4 @@
-.\" $OpenBSD: sftp.1,v 1.121 2018/11/13 07:22:45 schwarze Exp $
+.\" $OpenBSD: sftp.1,v 1.122 2018/11/16 02:30:20 djm Exp $
 .\"
 .\" Copyright (c) 2001 Damien Miller.  All rights reserved.
 .\"
@@ -22,7 +22,7 @@
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd $Mdocdate: November 13 2018 $
+.Dd $Mdocdate: November 16 2018 $
 .Dt SFTP 1
 .Os
 .Sh NAME
@@ -127,6 +127,7 @@
 and
 .Xr ssh-keygen 1
 for details).
+.Pp
 A
 .Ar batchfile
 of
@@ -141,11 +142,17 @@
 .Ic chgrp , lpwd , df , symlink ,
 and
 .Ic lmkdir .
+.Pp
 Termination on error can be suppressed on a command by command basis by
 prefixing the command with a
 .Sq \-
 character (for example,
 .Ic -rm /tmp/blah* ) .
+Echo of the command may be suppressed by prefixing the command with a
+.Sq @
+character.
+These two prefixes may be combined in any order, for example
+.Ic -@ls /bsd .
 .It Fl C
 Enables compression (via ssh's
 .Fl C