In Unix, device and file names are case-sensitive. In UNIX systems, environment variables can be defined using the shell. The binary font file is grfont.dat and the color-name database is rgb.txt . File name for the binary font file. The value of the variable should be a color name defined in the color-name database.
Color names are case-insensitive and embedded spaces are ignored.
The value of the variable should be a color name defined in the color-name database. On devices without a color lookup table, changing the background color only affects the color of elements explicitly drawn in color index 0. It will have no effect on programs that already include these calls. On some devices, buffering output can lead to large improvements in speed, but enabling buffering may upset synchronization between graphical output and other program activity. In addition to these environment variables, several device drivers use device-specific environment variables.