[EMBOSS] Can not install emboss on mandrake 9.2

[Sony]

Dear friends

I try to install emboss 2.8.0 on my mandrake 9.2, I have already done 
./configure prefix=/usr/local/emboss/, make, make install, but after I 
modify bashrc with the following suggested code " 
PLPLOT_LIB=/site/prog/emboss/lib PATH=/site/prog/emboss/bin:\$PATH export 
PLPLOT_LIB PATH" then the command line can not recognized common command 
such as ls, cp, etc except cd. When I try to log out, I can not back to my 
x windows because mandrake system reject my username and password (before 
changing the bashrc the username and password are working properly).
Does anyone know how to solve the problem? Do I have to change my 
distribution, once I have ever installed it in redhat 9, and it work 
properly without experiencing this case

Thank you very much for help

Sony Adi S