Bright background in termcap

Question

I'm trying to get a program I'm running to display a bright colored background, but the program won't apply the brightness increase, it instead shows a 'normal' colored background.

Let me add some details:

• I log into a server running Debian, through PuTTY, with the TERM variable set to putty (or manually do this using export TERM=putty).

• I first try whether bright backgrounds show up correctly at all, using

  echo -e "\e[43mHello\e[0m \e[103mWorld\e[0m"
  

  You see that \e[43m is the code for setting the background to yellow and \e[103m is the code for setting the background color to bright yellow. The image below shows that it actually works:

  

• Then I run the program I want to display such bright backgrounds. The program is the ACUCOBOL runtime. The manual says that it tries to read the TERM value and reads /etc/a_termcap by this value, selecting the (hopefully) proper terminal capabilities, if used on a *nix OS. The Windows client doesn't use any terminal capability info.

  The entry within the a_termcap file looks like this:

  putty|/PuTTY Colors:\
      :k1=\E[[A:k2=\E[[B:k3=\E[[C:k4=\E[[D:k5=\E[[E:k6=\E[17~:k7=\E[18~:\
      :k8=\E[19~:k9=\E[20~:k0=\E[21~:K1=\E[23~:K2=\E[24~:\
      :KE=\E[4~:KI=\E[2~:ku=\E[A:kd=\E[B:kl=\E[D:kr=\E[C:\
      :kh=\E[1~:al=\E[L:dl=\E[M:KX=\E[3~:li#25:DI=\E[m:kN=\E[G:kP=\E[I:\
      :cl=\E[;H\E[J:cm=\E[%i%d;%dH:ce=\E[K:cd=\E[J:DL:nd=\E[C:\
      :RV=\E[7m:HI=\E[0;1m:LO=\E[m:BL=\E[5m:UL=\E[4m:RB=\E[5;7m:RU=\E[4;7m:\
      :C1=\E[30m:C2=\E[34m:C3=\E[32m:C4=\E[36m:C5=\E[31m:C6=\E[35m:\
      :C7=\E[33m:C8=\E[37m:AC:\
      :B1=\E[40m:B2=\E[44m:B3=\E[42m:B4=\E[46m:B5=\E[41m:B6=\E[45m:\
      :B7=\E[43m:B8=\E[47m:UL@:RU@:\
      :GO=\016:GF=\017:\
      :GM=\161\170\154\153\155\152\166\164\167\165\156:
  

  The problem is that I can barely read these values, but the codes C1 … C8 and B1 … B8 refer to the foreground and background colors respectively, I think.

My guess is that the runtime is not aware of the codes \e[100m … \e[107m. How can I fix this?

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Edit

It seems that I can somehow can get black and white to be bright. Below a screenshot which allows both the bright and normal variants of black and white.

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Edit

I have changed the terminal emulator name to putty and set the TERM variable accordingly. I don't think, however, that it matters.

Answer 1

short: you can't

long: The ACUCOBOL support page explains what the termcap fields are. It knows about 8 colors, while your example expects to use the aixterm 16-color controls. Handling all 16 colors is beyond the ability of a termcap application (unless it cheats and formats its own strings rather than using tgoto).

You could make all of the backgrounds use bright colors, but you can't make some scenarios bright and some not. The places to modify would be B1 to B8 (colors 0-7 in the usual numbering convention):

:B1=\E[40m:B2=\E[44m:B3=\E[42m:B4=\E[46m:B5=\E[41m:B6=\E[45m:\
:B7=\E[43m:B8=\E[47m:

replacing 40 by 100, 41 by 101, etc.

By the way, TERM=linux is inconsistent with the example of an escape sequence which you gave (since Linux console's 16 colors are achieved by combining bold with colors 0-7, i.e., replacing 40 by 40;1, etc). You could copy that entry and change the name in the first line

linux|/Linux system console:\

to something more suitable, e.g.,

putty|bright-backgrounds:\

A termcap description cannot produce values in two ranges (40-47, 100-107 for example) since it doesn't support expressions. A terminfo description (not supported by ACUCOBOL, apparently) can do this. For example, ncurses has a 16-color Linux description. There are similar descriptions for other terminals, including whatever terminal you are actually using.