I had trouble when reinstalling the GSAS+EXPGUI package on my Ubuntu 8.04 because of some problem with the tcltk library. Here it is how to solve two problems :

First download the GSAS+EXPGUI package for linux and extract it where you want the package to be installed. In fact, no installation is needed as the extraction gives you the program itself. If you try to run expgui, you should run on a error stating that you don’t have « wish ». To get it install tk8.4 either by doing

 sudo apt-get install tk8.4

or simply using synaptic/adept to grab it.
After that, if you try to run expgui again you will see that a prompt telling you «  »Error loading the BWidget package: This should not happen if you use the version of Tcl/Tk (tcl84+.exe) distributed with EXPGUI ». But if you try to do what is on the GSAS homepage, as to say

 /myprogs/gsas/tcltk84+ /myprogs/gsas/expgui/expgui

you will run into an error also. The first error about the BWidget package is in fact more like a warning and it should not stop the script. To avoid breaking the script, just comment the lines with this statement in your expgui file like this :

 #if [catch {package require BWidget}] {

#    set msg "Error loading the BWidget package: This should not happen if you use the version of Tcl/Tk (tcl84+.exe) distributed with EXPGUI"

#    MyMessageBox -parent . -title "BWidget load error" \

#	-message $msg -icon error -type Error -default error \

#	-helplink "debug_tcltk.html"

#    destroy .

#}

Finally, if you try to run expgui it will complain about blt not being present. An installation of blt via synaptic or adept or using

 sudo apt-get install blt

should get rid of the last problem.
Now you should be able to run the GSAS+EXPGUI program on your Ubuntu machine. I don’t know if it works for other linux distro but I would be glad to hear it.