I need to log in to a clearcase repository via command line and make some basic changes.
Do I need to use cleartool for this, or can I log in via putty ?
cleartool
is your best approach, provided that you are using the full ClearCase client (instead of CCRC, which uses a different CLI).
Don't forget you don't have to open a cleartool session.
You can type several cleartool commands, each in their own cleartool session.
So to access a ClearCase repository (a Vob, within a view), you need to:
cleartool startview myView
cd /path/to/your/view/vob
Now if you had to actually connect to the Vob server, and do some administration changes, then yes, putty would be a way to do that. But you would still execute some cleartool command once connected to the server.