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Tip 1312 Printable Monobook Previous Next

created 2006 · complexity basic · author lpenz · version 6.0


XTerm and most other modern terminal emulators support 256 colors, you can use a script to check if your terminal supports 256 colors.

To enable colors on XTerm you will need to run the configure scripts with the --enable-256-color switch, in addition you may also need to set your TERM environment variable to xterm-256color.

For bourne shells (bash, zsh, pdksh) this is done in ~/.profile:

if [ -e /usr/share/terminfo/x/xterm-256color ]; then
        export TERM='xterm-256color'
else
        export TERM='xterm-color'
fi

Or for csh shells this is done in ~/.cshrc:

setenv TERM xterm-256color

See http://frexx.de/xterm-256-notes/ for more information about 256 colors on XTerm


To enable 256 colors in vim, put this your .vimrc before setting the colorscheme:

set t_Co=256

You may also need to add:

set t_AB=^[[48;5;%dm
set t_AF=^[[38;5;%dm

Your colors should at least look a little different. For full effect, use a colorscheme that supports 256 colors like desert256, inkpot, 256-grayvim, or gardener.

References

See also

Comments

Setting $TERM in the shell profile is generally a bad idea, since you may wish to use different terminals. It is preferable to add it to .Xdefaults (or similar file read by X applications):

XTerm*termName:         xterm-256color

Also, if the terminfo file is correct, there's no need to set 't_Co' in Vim. It will ask the terminal for that value. (Spiiph 11:39, 11 August 2009 (UTC))


Manually overriding the TERM setting is one of the most disgusting things I know of. I make sure all my machines have the extra set of Terminfo files, then I use the following logic in my .bashrc (which gets sourced from .bash_profile if $PS1 is set):

The entire system runs smoother if TERM is set properly. Overriding it to incorrect settings can produce strange problems which don't exist when using a different terminal emulator. The existence of poorly written terminal emulators using bogus TERM values results in application developers "working around" issues with their Terminal applications which, in turn, causes Terminal applications to not behave as you would expect. Now we have terminal applications sending color escape sequences when the terminal is monochrome, and we have some terminal application forcing xterm-style 256-color codes to terminals regardless of whether the terminal supports it. It makes me sad, as it is bad design breeding more bad design.

When the terminal emulator supports it, you should always override the TERM setting to the correct setting for your terminal. (Your terminal is not Xterm unless it supports Tektronix mode.)

All moderm terminal emulators support setting the TERM variable except for the Gnome Terminal.

Here's what to set the TERM entry for, based upon your terminal emulator:

  • PuTTY - putty-256color
  • rxvt - rxvt-256color
  • Eterm - Eterm-256color
  • Konsole - konsole-256color
  • XFCE's Terminal - gnome-256color

XFCE's Terminal uses the same library as the Gnome Terminal to create the virtual terminal, so it actually makes sense to use the same TERM setting for the two terminal emulators. This logic applies in other cases, if an application uses Konsole's or rxvt's code to perform terminal emulation, you can accurately and properly use that application's TERM setting.

I use the following code to catch gnome-terminal and automatically set the TERM correctly for xterm:

if [ "$TERM" = "xterm" ] ; then
    if [ -z "$COLORTERM" ] ; then
        if [ -z "$XTERM_VERSION" ] ; then
            echo "Warning: Terminal wrongly calling itself 'xterm'."
        else
            case "$XTERM_VERSION" in
            "XTerm(256)") TERM="xterm-256color" ;;
            "XTerm(88)") TERM="xterm-88color" ;;
            "XTerm") ;;
            *)
                echo "Warning: Unrecognized XTERM_VERSION: $XTERM_VERSION"
                ;;
            esac
        fi
    else
        case "$COLORTERM" in
            gnome-terminal)
                # Those crafty Gnome folks require you to check COLORTERM,
                # but don't allow you to just *favor* the setting over TERM.
                # Instead you need to compare it and perform some guesses
                # based upon the value. This is, perhaps, too simplistic.
                TERM="gnome-256color"
                ;;
            *)
                echo "Warning: Unrecognized COLORTERM: $COLORTERM"
                ;;
        esac
    fi
fi

Then I provide additional logic to make sure it falls back if there are missing Terminfo files:

SCREEN_COLORS="`tput colors`"
if [ -z "$SCREEN_COLORS" ] ; then
    case "$TERM" in
        screen-*color-bce)
            echo "Unknown terminal $TERM. Falling back to 'screen-bce'."
            export TERM=screen-bce
            ;;
        *-88color)
            echo "Unknown terminal $TERM. Falling back to 'xterm-88color'."
            export TERM=xterm-88color
            ;;
        *-256color)
            echo "Unknown terminal $TERM. Falling back to 'xterm-256color'."
            export TERM=xterm-256color
            ;;
    esac
    SCREEN_COLORS=`tput colors`
fi
if [ -z "$SCREEN_COLORS" ] ; then
    case "$TERM" in
        gnome*|xterm*|konsole*|aterm|[Ee]term)
            echo "Unknown terminal $TERM. Falling back to 'xterm'."
            export TERM=xterm
            ;;
        rxvt*)
            echo "Unknown terminal $TERM. Falling back to 'rxvt'."
            export TERM=rxvt
            ;;
        screen*)
            echo "Unknown terminal $TERM. Falling back to 'screen'."
            export TERM=screen
            ;;
    esac
    SCREEN_COLORS=`tput colors`
fi

Note that after this is done I know that TERM is valid and as correct as I can get it in the current environment.

In the rest of my init scripts I can also check SCREEN_COLORS and tweak things (like my PS1) based upon the palette available.

With the terminal set properly, you don't need to manually tweak any Termcap/Terminfo settings anywhere, and all applications that support 256 color mode can use it.

(Steven Black 20:34, June 22, 2010 (UTC))

Thanks, good info! Ubuntu (I've checked Hardy and Lucid) only ships with some basic terminfo definitions. sudo aptitude install ncurses-term will get you the additional ones for 256 colors. -- Inkarkat 11:37, June 23, 2010 (UTC)

LXTerminal works in 256 color mode, but you will need to load a color profile like "colorscheme desert256" --Kanliot 17:03, April 7, 2012 (UTC)

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