On UNIX you use the cleartool lscheckout command from the system prompt.
Here are some examples of the lscheckout command formats you might find useful.
When including the -long option in the command, Rational® ClearCase® includes the name of the view to which the element is checked out.
With the -me option, Rational ClearCase lists only those elements that you have checked out.
The -cview option narrows the search to elements checked out in the current view.
The -user option lets you specify the username of a team member.
cleartool checkout -comment "adding address" -activity "update_address" author.txt