If you want csh, install this package:
    http://www.jdv.net/mkarchive/sys/shell/tcsh-6.06.bin.tar.gz 
 
Then type 'chsh' (or edit /etc/passwd) to make 'csh' or 'tcsh' your
default shell.
 
zsh is also available at the MkArchive.
 
jonh@cs.dartmouth.edu
 
A good way to edit the /etc/passwd file is with the command vipw. You must also
make sure the shell you want to use is in the /etc/shells file.
 
jcarr@linuxppc.org
 
The ONLY way you should directly edit the /etc/passwd file is with vipw.
While not entirely necessary on our version of linux, in many other unixes
vipw does some maintainance after you are done editing, and directly 
editing /etc/passwd just wont work.  So, its a good habit to get in to.
 
slipcon@cs.jhu.edu

If your system happens to crash while using vipw, you will notice that
you are locked out of the passwd file, even if you are root.

You  can regain access to the passwd file by deleting the file named
/etc/ptmp  (it might be called something else) which is essentially
a lock file generated by vipw to prevents outside changes while
you are making the edits.

 jjv200@acf2.nyu.edu