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Comment by KrisJordan | Hacker News Reader

To get a red prompt drop this line in your ~/.bashrc file on your production server:

PS1='\[\e[1;31m\][\u@\h \W]\$\[\e[0m\] '

We use this in our production environments and the red prompt, though not as jarring as a red background, is still scary enough to serve its purpose.

One upside in setting this up on the server, as opposed to local like the OP, is that all connections in will get the red prompt.

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To avoid cryptic looking escape sequences, one could have the colour codes named in their .?shrc file [1]:

  txtblk='\e[0;30m' # Black - Regular
  txtred='\e[0;31m' # Red
  txtgrn='\e[0;32m' # Green
  txtylw='\e[0;33m' # Yellow
  txtblu='\e[0;34m' # Blue
  txtpur='\e[0;35m' # Purple
  txtcyn='\e[0;36m' # Cyan
  txtwht='\e[0;37m' # White
  bldblk='\e[1;30m' # Black - Bold
  bldred='\e[1;31m' # Red
  bldgrn='\e[1;32m' # Green
  bldylw='\e[1;33m' # Yellow
  bldblu='\e[1;34m' # Blue
  bldpur='\e[1;35m' # Purple
  bldcyn='\e[1;36m' # Cyan
  bldwht='\e[1;37m' # White
  unkblk='\e[4;30m' # Black - Underline
  undred='\e[4;31m' # Red
  undgrn='\e[4;32m' # Green
  undylw='\e[4;33m' # Yellow
  undblu='\e[4;34m' # Blue
  undpur='\e[4;35m' # Purple
  undcyn='\e[4;36m' # Cyan
  undwht='\e[4;37m' # White
  bakblk='\e[40m'   # Black - Background
  bakred='\e[41m'   # Red
  badgrn='\e[42m'   # Green
  bakylw='\e[43m'   # Yellow
  bakblu='\e[44m'   # Blue
  bakpur='\e[45m'   # Purple
  bakcyn='\e[46m'   # Cyan
  bakwht='\e[47m'   # White
  txtrst='\e[0m'    # Text Reset

[1] https://wiki.archlinux.org/index.php/Color_Bash_Prompt

I have a similar section in my .bashrc via a somewhat hackish loop (or two):

  ESC=$'\x1b'

  # Terminal color escapes
  colornames=(BLACK RED GREEN YELLOW BLUE MAGENTA CYAN)
  for i in ${!colornames[@]}; do
  	eval "${colornames[$i]}=\"${ESC}[3${i}m\""
  	eval "BG${colornames[$i]}=\"${ESC}[4${i}m\""
  done

  # There are holes in this sequence, so it doesn't loop nicely
  BOLD="${ESC}[1m"
  DARK="${ESC}[2m"
  UNDERLINE="${ESC}[4m"
  BLINK="${ESC}[5m"
  INVERSE="${ESC}[7m"
  RST="${ESC}[m"

  styles=(BOLD DARK UNDERLINE BLINK INVERSE RST)

  # and the PS1-safe versions of the above
  for i in ${colornames[@]} ${colornames[@]/#/BG} ${styles[@]}; do
  	eval "PS$i=\"\\[\$$i\\]\""
  done

Having color escapes in shell variables comes in handy from time to time (like faking 'colordiff' with sed).

I do that in bash for root/non-root users (root is red, non-root is blue):

    if [[ ${EUID} == 0 ]] ; then
        PS1='\[\033[01m\][ \[\033[01;31m\]\u@\h \[\033[00m\]\[\033[01m\]] \[\033[01;32m\]\w\[\033[00m\]\n\[\033[01;31m\]\$\[\033[00m\]> '
    else
        PS1='\[\033[01m\][ \[\033[01;34m\]\u@\h \[\033[00m\]\[\033[01m\]] \[\033[01;32m\]\w\[\033[00m\]\n\[\033[01;34m\]\$\[\033[00m\]> '
    fi

Interesting to think about using it across servers, though.

I used to have a different prompt color when SSH_CONNECTION was in my environment, to distinguish local terminals from remote connections. And also root/non-root, although I didn't know about $EUID and used the less-effective $(id -u).

Konsole does this automatically, at least on openSuSE linux.

It's actually just the default bash config on openSUSE, nothing to do with Konsole. It works on text-mode VTs, via ssh, etc.

I do exactly this as well as add a little blurb in motd saysing that this machine is production, tread carefully. This seems to solve a great deal of mistaken identity problems.

Is there any way to set this on directory level? I do my development in my /home/XYZ folder, and production is in /usr/local/www/XYZ and it would be great if I could set the background to red in the production dir (if I happen to wander into it somehow (which I really almost never do)).

You could put a shell script around cd that checks the current working directory every time you cd and alerts you appropriately.

A little clunky, I'll admit. I'd like to hear any more graceful solutions.

From man bash, the variable PROMPT_COMMAND:

  If set, the value is executed as a command prior to issuing each primary prompt.

e.g.:

  PROMPT_COMMAND='[[ "$PWD" =~ ^/sensitive/area ]] && PS1="be careful: " || PS1="normalprompt: "'

Pro tip: In Terminal.app you need the checkbox "Display ANSI colors" checked.

I prefer:

PS1="\[\e[1;31m\]$PS1\[\e[0m\]"

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