Newsgroups: net.unix-wizards
From: hoey@NRL-AIC.arpa (Dan Hoey)
Date: Fri, 17-Oct-86 13:47:26 EDT
Subject: Do not use blank lines in /etc/passwd

  Date: Mon, 25 Aug 86 11:15:24 edt
  From: sscalsk@nswc-wo.arpa

  Anybody ever had a blank line as the first line in your password
  file?  It happened to me a few weeks ago and the system would not
  let any user at all log on.  Su did not work either....

At least in vanilla 4.2, having blank lines anywhere in your password
file opens a security hole that I will forbear to discuss on this
list.  I have not verified this on other systems, but I advise you to
stick to the standard format.  If you want to insert blank lines for
readability (which is how I discovered the bug) use nearly-blank lines
like

x:*:0:0:
::

assuming that "x" is not a user on your system.

Dan Hoey
hoey@NRL-AIC.ARPA