On your sytem drive, you will find a file called S:Shell-Startup. One of the entries is:
Prompt "%N.%S> "
For a black shell, you could change this to:
Prompt "*e[>1m*e[33;41m%N.*e[30m%S>*e[32;41m "
Now save this change to S:Shell-Startup.Black or any other name you might fancy. Your Shell icon in SYS:System has a tooltype called FROM. Default this is:
FROM=S:Shell-Startup
If you want to always use a black shell, change this to:
FROM=S:Shell-Startup.Black
(or clone the current icon and thus create one that mentions Black Shell or whatever)
See below for a bit more information about all the codes that are being used in above example:
Esc[0m = Resets graphics modes to defaults
Esc[1m = Use Bold
Esc[30m = Use Text color0 = Grey
Esc[31m = Use Text color1 = Black
Esc[32m = Use Text color2 = White
Esc[33m = Use Text color3 = Blue
Esc[40m = Use Text Background color0 = Grey
Esc[41m = Use Text Background color1 = Black
Esc[42m = Use Text Background color2 = White
Esc[43m = Use Text Background color3 = Blue
Esc[>1m = Use Console Background color1 = Black
*e = Esc
Prompt "*e[>1m*e[33;41m%N.*e[30m%S>*e[32m "
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Sets the console background colour to Black
Prompt "*e[>1m*e[33;41m%N.*e[30m%S>*e[32m "
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Sets text colour to Blue, text background to Black and displays shell number (%N)
Prompt "*e[>1m*e[33;41m%N.*e[30m%S>*e[32m "
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Sets text colour to Grey and displays Source (%S)
Prompt "*e[>1m*e[33;41m%N.*e[30m%S>*e[32m "
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Sets text colour to White and adds a space