tl;dr screen says that it supports 8 colors, even when started with $TERM=xterm-256color in the environment. Please provide full 256 color support and set TERM=screen-256color.

+++ This bug was initially created as a clone of Bug #1165439 +++

Description of problem:
I found that gnome-terminal no longer sets COLORTERM, and thus 256term.sh doesn't patch up TERM=xterm or TERM=screen to their 256color variants.

Version-Release number of selected component (if applicable):
initscripts-9.56.1-4.fc21.x86_64
gnome-terminal-3.14.2-1.fc21.x86_64

How reproducible:
100%

Steps to Reproduce:
1. Open gnome-terminal
2. echo $TERM
3. Run screen/tmux
4. echo $TERM

Actual results:
First "xterm", then "screen".

Expected results:
On F20, it would get "xterm-256color" and "screen-256color".
COLORTERM was still being set by gnome-terminal at that time.

Additional info:

commit 1d5c1b6ca6373c1301494edbc9e43c3e6a9c9aaf
Author: Christian Persch <chpe>
Date:   Sat Apr 26 19:13:21 2014 +0200

    screen: Stop setting COLORTERM env var
    
    COLORTERM is a long-obsolete slang-only variable used to work around
    broken termcap/terminfo entries.

https://git.gnome.org/browse/gnome-terminal/commit/?id=1d5c1b6ca6373c1301494edbc9e43c3e6a9c9aaf

--- Additional comment from Josh Stone on 2014-11-18 20:05:50 EST ---

As a workaround, I've added this to my .bashrc, before global files are sourced:

if test -z "$COLORTERM" &&
    readlink /proc/$PPID/exe | grep -q gnome-terminal
then
    export COLORTERM=gnome-terminal
fi

Obviously, that can only check the immediate parent process, but so far it's ok.

--- Additional comment from Zbigniew Jędrzejewski-Szmek on 2014-11-20 19:42:33 EST ---

Whoah, what a mess ;)

So, gnome-terminal sets a $TERM entry which does not advertise full capabalities. Instead of changing that, we try to fix it up in the shell using a hacky scripts. This does not make any sense to me.

(Even if there were buggy programs which refused to work with TERM=xterm-256color, which I guess was the primal reason why it was not set properly when xterm or gnome-terminal gained 256 color support, they most likely have been fixed, since 256term.sh has been setting TERM=xterm-256color for many years now. So even if there was a reason no to do it, there isn't one now.)

Let's fix this properly. After-the-fact guessing whether a terminal supports 256 colors is not possible to do cleanly [1]. The only sane way is to set it properly from the terminal emulator program.

So I propose a two step procedure:

1. Make gnome-terminal, xterm, screen, tmux, and whatever else set a $TERM entry which advertises 256 colors. I'll file bugs for gnome-terminal and screen.

2. Wait a bit for 1. to happen, then drop 256term.* from initscripts.

The rationale is that when 1. is done, the 256term.* scripts will be noops, so doing things in this order should provide a smooth transition.

[1] http://unix.stackexchange.com/questions/23763/checking-how-many-colors-my-terminal-emulator-supports/23789#23789