SeqLab or another X-program won't display on your PC screen?

Your system administrator has set it up so that, as long as you start the Xserver on your PC, seqlab will automatically display correctly on your PC. 

If seqlab cannot display on your PC screen, you will get an error message.There are several possible reasons for this to happen. The most common reasons are described here.

General Reason:

First of all, if, when you type "seqlab&", you get an error message back that says:  "command not found", your environment has gotten thoroughly confused, and the easiest way to fix that is to log out and to log back in again. If that fails to fix that error message from seqlab, copy your screen and email it to Stuart Brown so that they can see exactly what you typed, what the error message was, and will be able to figure out the fix.

You must have an X-server package installed on your PC! (White Pine's eXodus, Hummingbird eXcede, MacX, or others)

Specific Reasons:

(1) Your DISPLAY variable is not set correctly on the Unix system. This is the most common error message returned from SeqLab when it attempts to display, but it is actually symptomatic of either of the 2 problems outlined here.

Error Message:

molbio /dr2/home2/admin/cprice/root> seqlab&
[1] 5517
molbio /dr2/home2/admin/cprice/root> 
SeqLab cannot open your display.
Please do a setenv DISPLAY ... and try again.
Make sure your display authorizes connections from your host.
Consult your system manager for help.

Remedy:

    (a) Find out where you are sitting (the network address). 

On Digital Unix systems, type "who -Mm".  In the output from these commands, find the line with your name.  The right hand end of the line shows the network address. Examples:

Example from a Digital System:

gsaf.unmc.edu> who -Mm
cprice      ttyp3       Mar  6 08:48            (windsurf2.unmc.edu)

Finger provides information on all users logged into the system:

molbio /dr2/home2/admin/cprice/root> finger
Login 	Name 		TTY 	Idle 	When 		Where
wchaney Bill Chaney 	pts/1 	7 	Fri 10:19 	wchaneypc.unmc.edu 
lchaney Linda Chaney 	pts/2 	13 	Fri 11:17 	trex.unmc.edu 
pwilder Phil Wilder 	pts/3 	20 	Fri 10:57 	137.197.151.41 
cprice 	Chad Price 	pts/5 	Fri 	11:04 		bdl-windsurf2.unl.ed
molbio /dr2/home2/admin/cprice/root> 

Example of who -M  from a Digital Unix System:

biocomp.unl.edu /usr/users/cprice> who -M
cprice 		ttyp1 	May 8 09:29 (gcg-mng) 
cprice 		ttyp2 	May 8 11:31 (bdl-windsurf2.unl.edu)
bjadams 	ttyp4 	May 8 09:54 (plp-bjadams2.unl.edu)
rdonis 		ttyp5 	May 7 21:42 (vs-rdonis4.unl.edu)
pblum 		ttyp6 	May 8 08:50 (bdl-pblum.unl.edu)
pherman 	ttyp8 	May 6 13:44 (bdl-dweeks3.unl.edu)
cprice 		ttyp9 	May 8 10:46 (gcg-mng) 
biocomp.unl.edu /usr/users/cprice> 

On Digital Unix systems, it is also possible to see only the results of the who command for your own current login by typing  who -mM :

gsaf.unmc.edu> who -mM
cprice      ttyp3       Mar  6 08:48            (windsurf2.unmc.edu)
gsaf.unmc.edu> 

Once you know where you are, set your DISPLAY variable to match that address:

For csh and tcsh users:

setenv DISPLAY bdl-windsurf2.unl.edu:0.0

For ksh users:

DISPLAY=bdl-windsurf2.unl.edu:0.0;export DISPLAY

Note that you must always end the setenv command with a ":0.0".  If you do not, then your X-program like seqlab will not be able to display on your screen.

(2) You have not started the X-server on your PC.

The error message for this may be the same as for an unset environment variable:

molbio /dr2/home2/admin/cprice/root> seqlab&
[1] 5517
molbio /dr2/home2/admin/cprice/root> 
SeqLab cannot open your display.
Please do a setenv DISPLAY ... and try again.
Make sure your display authorizes connections from your host.
Consult your system manager for help.

Remedy:

On a Mac, double click on the icon for eXodus.

On a PC, find the  X-server program (eXodus or eXcede or ???) and start it.

(3) At this point, if you have done both of the above steps, you can start your X-based program on your GCG or other Unix server and it will be able to find your PC and display on it's screen.