10

My local Linux machine has coloured terminal output like this;

enter image description here

When I SSH to a pfSense/BSD box it changes the colours like this;

enter image description here

Even when I SSH from to a machine that doesn't have a coloured local terminal output, and SSH from there to this pfSense/FreeBSD box it enables coloured output, and starts producing unwanted coloured output/

Is there something I can change locally so that when I SSH to the pfSense box from either my local machine or via an intermediary machine, my client will ignore the remote colour settings. Ideally I want to stay in black and white, two tone standard background and text colour only?

  • What terminal application are you using? – gertvdijk Dec 20 '12 at 11:28
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    Here I am running Mint Linux 13, so it's Xfce Terminal Emulator 0.4.8. – jwbensley Dec 20 '12 at 11:32
  • I know this isn't what you are asking for, but have you considered changing your terminal settings to white [or light gray] text on a black background? That is the basic color scheme that most things are designed to work with. Or you could change your prompt settings on the remote machine (probably in .bash_profile) to have better colors or no colors at all. – Random832 Dec 20 '12 at 15:57
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    Normally I do something like TERM=xterm-mono ssh user@host to get that setting in the remote environment. – ott-- Dec 20 '12 at 17:11
6

Colours in your terminal appear because the tty sends ANSI-encoded control sequences to tell your terminal to change colours. Some, if not most terminal application can be configured to ignore this and just display all text in one colour.

In xterm, you can use the -cm option. For Konsole, one can change the mapping of all colours to the same. Your XFCE terminal application may have similar options.

5

Changing the TERM variable to some entry that is compatible but doesn't have colour support might work. Like:

TERM=xterm-old

Basically, you need a TERM known by the FreeBSD system termcap or terminfo database for which TERM=the-term tput colors doesn't return a positive number, and for GNU ls, one for which dircolors -p | grep -x 'TERM the-term' returns nothing. It may still not work for applications that output colour escape sequences regardless of whether the terminal claims to support it or not.

Alternatively, you could use GNU screen to disable colors, like (zsh syntax):

screen -c =(printf %s\\n "termcapinfo * 'AF=\E[1m:AB=\E[7m'") ssh ...

That would enable bold for every attempt to set the foreground colour and reverse for every attempt to set the background one.

I think it all boils down to the fact that FreeBSD assumes that the terminal background is black (or at least dark). Where you using xterm instead of xfce-terminal, you could dynamically change the background and foreground colour and/or the individual colours to set different colour profiles. That is done through escape sequences, but you can also use the xtermcontrol command that makes it easier.

  • Tried that - doesn't work for me. export TERM=vt100 preceding ls --color still shows colorized output. – gertvdijk Dec 20 '12 at 12:22
  • @gertvdijk Good point. It seem there's a bug in GNU ls which by default hard codes vt100 as being a terminal with colour support. I've changed that do xterm-old which doesn't have that problem but might not have a terminfo entry on FreeBSD. – Stéphane Chazelas Dec 20 '12 at 12:28
  • Well, it doesn't prevent other programs from outputting colour as well - i.e. byobu. I'm on Ubuntu 12.04 btw. – gertvdijk Dec 20 '12 at 12:29
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    @gertvdijk. Like I said. It only works for well behaved programs that use $TERM and the termcap/terminfo databases (via curses or other terminal APIs) instead of hardcoding the escape sequences. – Stéphane Chazelas Dec 20 '12 at 13:07
  • what can i use to remove all escape sequences that can change terminal state after EOF? – Janus Troelsen Aug 11 '15 at 20:10
1

In case you don't want to modify your ~/.bashrc which I'm sure contain something like export PS2=.....+colors...... :

On the linux Console, try either TERM=linux-m1b or TERM=linux-m2 to get monochrome as "Gray/White/Black and Dim" for linux-m1b or "Green/White/Black and Blue" (vintage!) for linux-m2 ...

With Putty (there is a port for Mac users), use TERM=putty-m1b and TERM=putty-m2 instead ...

This will do exactly what you need but: You'll need a recent terminfo database for that or get it from there if necessary: wget http://canal.chez.com/linux.ti ; tic -x linux.ti

Alex. PS: xterm-mono seems not to exist anymore.

1

Type the following command to remove it:

$ ls --color=none

or use unalias to remove it:

$ unalias ls
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    Isn't that just for the ls commad though? – jwbensley Dec 20 '12 at 11:31
  • ls is aliased to "ls --color=tty" – Len Dec 20 '12 at 11:34
  • Yes. I know. But all my terminal output is coloured output, not just the ls command, so as per my previous comment: isn't that just going to stop ls producing coloured output, everything else will still be coloured though? – jwbensley Dec 20 '12 at 11:35
  • yes only the ls portion – Len Dec 20 '12 at 11:39
  • But I want to disable all terminal colours?! – jwbensley Dec 20 '12 at 11:40
-1

First, check your default alias:

alias

alias ls-'ls --color=auto

If the doesn't work and you need a quick workaround. Try this ls and awk pipe:

vi /usr/local/bin/list
#!/bin/bash
ls $1
exit

set the perms 744.
One safe place for this would be /usr/local/bin Make sure your PATH includes /usr/local/bin.

Again use discretion.

One thing… the colors are meant to flag directories… turning off the ls="ls --color=auto" leaves only names… ls -aF or ls -F will append the directory names with /. So I would suggest that you be aware. You could alias ls="ls -aF" or alias ls="ls -F".

  • 2
    How does this answer provide an answer to the original question? – jwbensley Jan 25 '17 at 19:05
  • Welcome to Stack Overflow! I recommend you take the tour. – Stephen Rauch Jan 25 '17 at 19:24

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