i have ubuntu 10.04 on my sytem, i run command apt-get install csh on the system and try to change the shell by command chsh -s but now the prob is when i try to login the system by ssh i am not able to login by any user account except one and try to change the user su - root it is showing cannot execute c: no such file or directory and look in the /etc/passwd file for root account in shell field C is written in place of /bin/sh help me out to restore the settings