on Sat, Oct 28, 2000 at 10:06:56AM -0700, Peter Jay Salzman (p@belial.ucdavis.edu) wrote:
> also, i noticed that some accounts which are disabled are given a shell of
> /bin/false:
>
> ftp:x:100:65534::/home/ftp:/bin/false
>
> tiger seemed to hate this too. i tried playing around with /bin/false.
> can't seem to figure out what it is. whatever it is, it's tiny. only 4 kb
> long.
See man false.
false - do nothing, unsuccessfully
Think of it as /dev/null, /dev/full, /dev/zero, or the lo loopback
networking interface. Or zero (0), for that matter.
Doing nothing can be incredibly valuable. As the Zen saying goes:
"Don't just do something, stand there!". /bin/true and /bin/false do
nothing. true exits with a successful status, false exits with a
nonsuccessful status.
This is useful for accounts which you don't want to have any successful
shell access, it can be handy in shell scripts to force a failure
condition, or elsewhere. In the same sense, /dev/null discards bits (or
returns a null read), /dev/full is a file which is always full (write
produces error), /dev/zero returns an ASCII null, and the lo interface
allows tests of networking when no "real" networking interface is
available -- this is useful both in testing services, and in setting up
systems such as diald.
--
Karsten M. Self <kmself@ix.netcom.com> http://www.netcom.com/~kmself
Evangelist, Opensales, Inc. http://www.opensales.org
What part of "Gestalt" don't you understand? There is no K5 cabal
http://gestalt-system.sourceforge.net/ http://www.kuro5hin.org
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