rxvt/xterm colors
 

I just installed rxvt, it comes with black fonts and a white background, i want the opposite: white fonts on a black background.

I tried: rxvt -bg black -fg white and it works, but only for that session.

is there a way to make it permanently?

add it to your enviorment. E.g. for bash it's .bash_profile or .profile or .bashrc Check for what your shell provides.

I believe you can specify rxvt-specific stuff in ~/.Xresources, also. Check out the rxvt man page.