Difficulty using shell in Ubuntu Linux

[Bob Warren]

I now have an explanation as to why the shell in (Ubuntu) Linux seems to 
work sometimes, but not others: the HD path to the executable for 
launching MUST NOT CONTAIN BLANKS!

For example, this works like a charm:

   global myVar
   put "/home/bob/Desktop/folderwithnospaces/myprog" into myVar
   set the defaultFolder to "/home/bob/Desktop/folderwithnospaces"
   get shell(myVar)

This doesn't work at all:

   global myVar
   put "/home/bob/Desktop/folder with spaces/yourprog" into myVar
   set the defaultFolder to "/home/bob/Desktop/folder with spaces"
   get shell(myVar)

Exactly the same thing applies to the LAUNCH command.

Now what do I do?
Any ideas anyone?

Bob