As I said just braindumps 8-)
See the man page of respective shell.
However, these files are only read once, when you login to a system, so if you modify either of them you have to re-login or start a new shell on the system as they are not read dynamically. However you can force a re-read of the files, in bash this would be done with a dot:
and in csh/tcsh by the 'source' command: