TidBits 2013

• When we install Topspin, where does it store the default path information, to start the topspin script ?

Topspin stores this information in two files : 
/etc/profile.d/topspin.sh  
/etc/profile.d/topspin.csh

As can be inferred the former is used for a BASH shell and the latter for a c-shell or its derivatives.  The PATH invocation's syntax is different for the two types of shells and this is the reason for the existence of these two separate files.  

As an example, in my system, inside the topspin.sh file this is what I find : 

 PATH=/opt/topspin3/prog/bin/scripts:$PATH # created by TopSpin Installer

The above defines the global path for Topspin installation.
If you are installing Topspin in two different locations in parallel, for instance, both Topspin 2.1 and Topspin 3.0,  then only one of them will be sourced, when you enter the script name topspin on the shell command line. Which version of Topspin will be started will be decided by the global path defined in the file above.  Normally, you are not expected to kludge this file by hand, as is implied by the comment "created by Topspin Installer".   Having said that, if you change the path here by hand, it does work.