I'm using TCPIP for OS2 v 1.2.1 to telnet to an RS/6000 running AIX
3.2.3. I begin the connection by executing the tn.exe to host risc01.
After the login to the system, I would like to automatically start an
aixterm session. Currently I prompt the user for his local host name,
and use this name as the -display variable on the aixterm command.
The problem with this is it is too prone to error. If I do a who
command from the system console, it shows my login id AND my local
host name. Is this local host name stored in an environment variable
available to me to include in a login script which could automatically
start the aixterm session ? If so, how do I get to it ?
If not, is there some other way to accomplish what I'm trying to do?
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A: I will address your questions in the order presented.
1. Is the hostname from who stored in an environment variable?
The hostname in the forth column of the 'who' command is the name
of the system from which you are connecting. This name is taken
from the "/etc/utmp" database which is updated every time a user
logs in or out. However, the /etc/utmp file is a binary file and
thus cannot be easily accessed by shell scripts.
You can set the DISPLAY environment equal to the hostname from the
who command using a ksh command similar to the following:
DISPLAY=`who|grep $USER|tail -1|cut -f2 -d"("|cut -f1 -d")"`:0
Character Legend:
` = Single Back Quote | = Pipe (verticle bar)
The problem with the above command is that if the user is logged
directly into the machine (is not telneting in from another
machine), then the DISPLAY variable will be set to their who entry
followed by a :0. For example, if a user 'bob' logged into the
console issues the above, their DISPLAY variable will be set to:
bob hft/0 Oct 25 08:00 :0
Another problem with the above command is that it sets the display
variable to the name of the machine from which the user is
telneting. This is not always the correct machine to send output
to. For instance, if I am on an X-station named 'maca' with a
session on 'macb' and then telnet into 'macc', the above command
will set my display variable to 'macb'. This is not really what
is desired; I would prefer my display set to 'maca'.
Therefore, the above command should be used with care. In response
to your second question, I have written a sample script which
overcomes these problems at the sacrifice of transparency to the
user.
2. Is there another way to accomplish this?
You may wish to combine the above command with your prompting for
in the .profile file. It will prompt the user for a display
variable (displaying the hostname from the who command). If the
user hits , the hostname displayed will be accepted. If the
user enters a valid hostname, it will be accepted. But, if the
an invalid hostname is entered it will not be accepted and the user
will be prompted to try again.
Please note, the sample script below is to be used as an example of
how this can be done. IBM in no way supports this script.
Character Legend:
` = Single Back Quote | = Pipe (vertical bar)
. = Open square bracket . = Close square bracket
-------------------------BEGIN SAMPLE SCRIPT-----------------------
TDISPLAY=`who|grep $USER|tail -1|cut -f2 -d"("|cut -f1 -d")"`
if .. "$TDISPLAY" = "`who | grep $USER | tail -1`" ..
then
TDISPLAY="`hostname`"
fi
integer OKAY=1
while (($OKAY == 1))
do
echo -n "Please enter your display .$TDISPLAY.: "
read VAR
if .. "$VAR" = "" ..
then
VAR=$TDISPLAY
fi
if .. "`host $VAR 2> /dev/null | cut -f1 -d:`" ¢= "" ..
then
OKAY=0
fi
done
export DISPLAY=$VAR:0
-------------------------END SAMPLE SCRIPT-------------------------
To summarize, the 'who' command is obtaining the hostname from which
the user is logging in from the /etc/utmp database. Information about
the user is placed in this database when the user logs in. Although
the /etc/utmp file is in a binary format, the hostname from which the
user logs in can be obtained by parsing the output of the who command.
This does have problems, though, since it only displays which machine
the user is logging in from and not necessarily the correct machine
to send X output to. By integrating the output from this command with
your existing method of prompting for a display name, as well as
verifying that a valid hostname was entered, the result is a fairly
robust and user friendly system by which the DISPLAY variable is
automatically setup.
Note: With the DISPLAY variable set, it is not necessary to use the
"-display" flag as aixterm will read the DISPLAY variable by default.
One general note on AIX Technical Support policy: unfortunately we
cannot write scripts for you, but somethimes we can provide sample
scripts or ideas on how to write a script. When a sample script is
provided, that script is purely an example of how something can be
done and the script is not supported by IBM.
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This item was created from library item Q652306 9SBLF
Additional search words:
ARISC CUSTORG ENVIRONMENT HOSTNAME IX JAN94 LOCAL OS2 OZNEW RISC SET
SETTING TCPIP VARI X-WINDOWS XWINDOWS 9SBLF
WWQA: ITEM: RTA000038609 ITEM: RTA000038609
Dated: 11/1996 Category: RISCOSO
This HTML file was generated 99/06/24~12:43:15
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