1. Through ps -p $$ you can know whether the system kernel belongs to bash or csh
2. Add the environment variables to be set in the two files ~/.cshrc and ~/.login through VI, these two files are under the directory of *adm HOME.
3. After modifying the file through VI, use: w !sudo tee % to save the file
4. Use the source command to make ~/.cshrc and ~/.login take effect respectively.