tty permissions (was Users and Groups)

[Mikkel L. Ellertson]

Tim wrote:
> 
> Just out of curiousity, I did a "ll /dev/tty*" and saw a strange mixture
> of ownership:
> 
<----------------------------[ SNIP ]--------------------------->

> 
> Various "tty"s were owned by root:tty if they had a double-digit number,
> or root:root if otherwise.  The "ttyS"s were owned by root:uucp (this
> box only has one or two serial ports - one's external, and I can't
> remember if there is an internal one).
> 
> I know tty and ttyS aren't the same thing, but it seems an odd mixture.
> 
A big part of it is that there are programs that are using
/dev/tty[0-7] and /dev/tty. These are the different virtual
consoles. Normally, if no-one if logged in, tty1 through tty6 have
mingetty running on them, running as root. In run level 5, tty7
normally will have a display manager running until someone logs in.

Try doing a command line login as a normal user, and look at the tty
that matched the VT number. It will be owned by that user that just
logged in. If you change the number of command line logins, or have
more then one X secession running, you will change the
ownership/permissions on a different number of the ttys. Ownership
can also be changed because they are being used by other programs. I
like to use a couple of ttys to display different outputs of
syslogd. They can also be handy to display the error output of a
program under test.

Now, as you noted, the /dev/ttyS* are different. These are physical
serial ports, not virtual ports. (Though there may be more device
entries then there are physical ports.) Exactly how the permissions
are set depends on the version of Fedora, and how you have
console.perms set. If you desire, you can set a serial port to be
owned by the person logged into the console. It is also possible to
have a symlink to a serial port and have the symlink managed by
console.perms.

Mikkel
-- 

  Do not meddle in the affairs of dragons,
for thou art crunchy and taste good with Ketchup!

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