I have the following users on my who list:
kye              p0       85.132.8.116     Tue06AM 13:11 -bash (bash)
casper           p2       frau.triohost.co Thu08PM    43 less -R -E -X
-Q -r -d
cdalten          p4       eecs.berkeley.edu  8:33PM     - w
chocnut          p5       pc8008.temp.co.l  7:06PM     6
/usr/local/bin/real/ly
najib            p6       magnifix.com.my   1:38AM 18:06 mutt
marcotap         p7       dsl-189-133-6-33  8:16PM    17 -bash (bash)


The problem is that some of them have a controlling terminal (ie their
terminal is written to utmp) and some don't (ie there is something like
/ftp/45678 instead of /dev/ttyp4 for example).  What would be the
easiest way to go down the list and determine who has a controlling
terminal and who doesn't?

The only thing I can think of is looping through utmp and seeing if
that user has a terminal number written to utmp. If they do, then have
it print back they have a controlling terminal. If not, then have it
print back they don't have a controlling terminal.

Ideas?

Chad

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2007-01-17, 17:41(-08), K-mart Cashier:
> I have the following users on my who list:
> kye              p0       85.132.8.116     Tue06AM 13:11 -bash (bash)
> casper           p2       frau.triohost.co Thu08PM    43 less -R -E -X
> -Q -r -d
> cdalten          p4       eecs.berkeley.edu  8:33PM     - w
> chocnut          p5       pc8008.temp.co.l  7:06PM     6
> /usr/local/bin/real/ly
> najib            p6       magnifix.com.my   1:38AM 18:06 mutt
> marcotap         p7       dsl-189-133-6-33  8:16PM    17 -bash (bash)
>
>
> The problem is that some of them have a controlling terminal (ie their
> terminal is written to utmp)

Controlling terminals are not related to utmp. A controlling
terminal is the terminal that sends you a SIGINT when the user
types CTRL-C and you are in its foreground process group or what
sends you a SIGTTIN when you try to read from it and are not in
its foreground process group.

You can know it with:

tty_of() { # arg: <pid>
if tty=$(ps -p "$1" -o tty=); then
case $tty in
("" | "?") return 1;;
(*) printf '/dev/%s\n' "$tty";;
esac
return 0
fi
return 1
}


--
Stéphane

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