undo.1: Add some words about the new fake transaction id warning.

Suggested-by: polachok

While here, add an "EXIT STATUS" section and fix a sentence about
hammer synctid (filesystem argument is not optional).

diff --git a/usr.bin/undo/undo.1 b/usr.bin/undo/undo.1
index 156fe9b..0129821 100644 (file)
--- a/usr.bin/undo/undo.1
+++ b/usr.bin/undo/undo.1
@@ -31,7 +31,7 @@
 .\" SUCH DAMAGE.
 .\" 
 .\" $DragonFly: src/usr.bin/undo/undo.1,v 1.5 2008/07/16 21:38:10 dillon Exp $
-.Dd May 31, 2008
+.Dd November 16, 2009
 .Dt UNDO 1
 .Os
 .Sh NAME
@@ -109,12 +109,21 @@ A simple index may be
 specified instead of a transaction id where 0 indicates the latest version
 and increasing values indicate older versions.
 .El
+.Sh EXIT STATUS
+.Ex -std
 .Sh EXAMPLES
 .Li "undo -d mytextfile"
 .Pp
 .Li "undo -o mytextfile.old mytextfile"
 .Sh DIAGNOSTICS
-Exit status is 0 on success and 1 on error.
+.Bl -diag
+.It "Warning: fake transaction id 0x..."
+While locating past versions of the file,
+.Nm
+came across a fake transaction id, which are automatically generated by
+.Xr hammer 5
+in case the file's directory entry and inode got bisected in the past.
+.El
 .Sh SEE ALSO
 .Xr hammer 8
 .Sh HISTORY
@@ -128,4 +137,4 @@ utility first appeared in
 HAMMER only synchronizes information to disk every 30 seconds or so and
 a quick file create / delete is done entirely in system memory and cannot
 be undone.  This can be worked around by running
-.Dq Ar hammer synctid Op filesystem .
+.Dq Nm hammer Cm synctid Ar filesystem .