7

I'd like to make happen in RHEL/CentOS 7.6

anytime you do su and become root I want the terminal prompt color in that terminal to become red for the duration of that su session. Type exit to go back to being whoever you were and I want the prompt color to go back to whatever the previous color was (black).

Same for an SSH window using putty logged in over the network: initially ssh in as user and have a default white shell prompt; do an su to root and I want the prompt to become red; type exit I want the prompt to go back to white.

so far i did this but it's not working 100%, the color stays red after you type exit and leave the su session and go back to being user.

/etc/profile.d/red_root_prompt.sh

if [ $UID -eq 0 ]; then
   PS1="\e[31m[\u@\h \W]# "
else
   PS1="[\u@\h \W]# "

Is there a way to make things happen the way I want? I only want it for bash shells.

Improve this question
3
  • Are you typing su or su -? I’d have thought the prompt would return to what ever it was before you elevated if you used the latter. Commented Nov 7, 2019 at 23:09
  • i only ever do just su, and the color thing has always worked in SUSE. Commented Nov 8, 2019 at 12:53
  • You probably want to use tput rather than embedding terminal-specific escape codes that will make a mess when you use some other terminal type. And don't forget \[…\] around non-spacing output, or Bash will miscalculate line lengths. Commented Jul 22, 2023 at 17:38

2 Answers 2

Reset to default
12

You can either add this to /etc/bash.bashrc or edit /etc/profile/

force_color_prompt=yes

    if [ "$LOGNAME" = root ] || [ "`id -u`" -eq 0 ] ; then
        PS1='\[\033[01;31m\]\u@\h\[\033[00m\]:\[\033[01;34m\]\w\[\033[01;34m\]#\033[00m\] '
    else
        PS1='\u@\h:\w\$ '
    fi

and you will get a prompt that looks like this. If you use a white background, change the last part after # to \033[01;30m\] so you can see the command text. I included that as a second example for reference .

Visual appearance

also if you add the following to \etc\bash.bashrc or ~/.bashrc:

export col_white='\033[00m'
export col_black='\033[01;30m'

export col_red='\033[01;31m'
export col_green='\033[01;32m'
export col_yel='\033[01;33m'
export col_blue='\033[01;34m'

You will be able to do :

$ echo -e $col_red red $col_blue blue $col_yel yellow $col_green green
 red blue yellow green

with the output looking like this:

enter image description here

EDIT: For some reason using variable expansion for the prompt breaks the carriage return (it locks it to the length of the variable, i.e. pushes it forward by n-many spaces corresponding to echo $col_blue,echo $col_white, and I have not found a good solution for this as of this moment, but using proper bracketing without variable substitution as above solves this issue. 

if [ "$LOGNAME" = root ] || [ "`id -u`" -eq 0 ] ; then
    PS1="$col_red\u@\h:$col_purple\w$col_green# $col_white"
else
    PS1="\u@\h:$col_blue\w$col_yel\$ $col_white "
fi
Improve this answer
1
  • I could achieve my favorite setting (similiar to yours but without the carriage return misrenderering or whatever) with this: if [ "$LOGNAME" = root ] || [ "id -u" -eq 0 ] ; then PS1='\[\033[01;31m\]\u@\h\[\033[00m\]:\[\033[01;34m\]\w\[\033[00;29m\]# ' else PS1='\u@\h \w : ' fi Plenty of trial and error on my behalf though; so please don't rely for certain on it. Commented Jul 27, 2020 at 11:47
3

for RHEL/CentOS 7.x I thought customized stuff like this was supposed to be under /etc/profile.d or in something like /etc/bashrc.local. That way any customization is preserved after updates when something like /etc/bashrc is might be changed or replaced.

for RHEL/Centos 7, I thought one should only need to put a file under /etc/profile.d/ having the corresponding suffixes for the shells they are for,

so I did /etc/profile.d/redrootprompt.sh having only

if [ "$LOGNAME" = root ] || [ "`id -u`" -eq 0 ] ; then

    PS1='[\[\033[01;31m\]\u@\h\[\033[00m\]:\w] : '

else
    PS1='[\u@\h \w] : '
fi

and this works great giving the look i wanted

red root prompt

it also works in a putty window which has black background and white text, but goes red after su to root and back to white on exit.

Improve this answer
1
  • As far as config, if you look at man bash there are different sets of configuration files that bash reads in depending on the mode of invocation. Both /etc/bash.bashrc and ~/.bashrc correspond to bash invoked in interactive mode, which is the default mode as long as your default shell is invoked as sh. The /etc/profile and ~/.profile files get read in when bash is invoked as a login shell and if you run echo $BASHOPTS , it will have login_shell as a listed parameter. Commented Nov 8, 2019 at 17:29

You must log in to answer this question.

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.