last: add note about empty files/entries to the man page

Fixes: https://github.com/util-linux/util-linux/issues/1609
Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/login-utils/last.1.adoc b/login-utils/last.1.adoc
index 6c7017cdd2cf2687f00117511bb2dac23d7af5ad..1157ae957168da8df7a800d01c3d874527a4a546 100644 (file)
--- a/login-utils/last.1.adoc
+++ b/login-utils/last.1.adoc
@@ -115,6 +115,8 @@ _/var/log/btmp_
 
 The files _wtmp_ and _btmp_ might not be found. The system only logs information in these files if they are present. This is a local configuration issue. If you want the files to be used, they can be created with a simple *touch*(1) command (for example, *touch /var/log/wtmp*).
 
+An empty entry is a valid type of wtmp entry. It means that an empty file or file with zeros is not interpreted as an error.
+
 == AUTHORS
 
 mailto:miquels@cistron.nl[Miquel van Smoorenburg]