XTerm & URxvt support 256color. Only the first 16 can be changed using resources currently, the rest can only be changed via command sequences ("escape codes").
From man console_codes
It is generally not good practice to hard-wire terminal controls into
programs. Linux supports a terminfo(5) database of terminal capabili‐
ties. Rather than emitting console escape sequences by hand, you will
almost always want to use a terminfo-aware screen library or utility
such as ncurses(3), tput(1), or reset(1).
'tput' command can initialize a terminal or query terminfo database.
To query the terminal support colors' types:
tput colors
it will output a number like 8,16,88,256.
To change the current foreground/background color on a terminal:
tput setf <256-color-code>
tput setb <256-color-code>
tput setaf <256-color-code>
tput setab <256-color-code>
NOTE:Only tput setab/setaf <256-color-code> can work in XTerm.
For example:
tput setaf 255;tput setaf 231;echo 'Microsoft gives you windows;Linux gives you a world'
It will print the sentence in color255 as foreground and color231 as background.
If you want to change the terminal's color configuration,there is a bash script I wrote,which can show 256color in terminal.
If you want to test font configuration,here is a bash script I wrote,it can test all kinds of font in fc-list on urxvt, and screenshot for you choice.The screenshot name is serial-num+font-name.png,and all the screenshots are saved in ~/pictures/shots/font-test-urxvt.
Dynamic control of xterm properties,such as colors,title,font,geomtry.
HomePage
GitHub