On RHEL6 and CentOS 6, /etc/bashrc sets PROMPT_COMMAND here:

case $TERM in
    if [ -e /etc/sysconfig/bash-prompt-xterm ]; then
        PROMPT_COMMAND='echo -ne "\033]0;${USER}@${HOSTNAME%%.*}:${PWD/#$HOME/~}"; echo -ne "\007"'
    if [ -e /etc/sysconfig/bash-prompt-screen ]; then
        PROMPT_COMMAND='echo -ne "\033_${USER}@${HOSTNAME%%.*}:${PWD/#$HOME/~}"; echo -ne "\033\\"'

All of these options, as far as I know, are printed invisibly. What is the use of this?

I know that PROMPT_COMMAND is to be executed before display the prompt (PS1 usually). I do not understand why echoing something that is not visible is of any use.


\033 is the octal code for the Esc (Escape) character, which is a good hint that the echoed strings in your PROMPT_COMMAND are terminal control sequences. Both sequences in your examples look like they set the terminal title to user@host:pwd.

The first case, xterm* sets the window name and icon title. For a detailed explanation, look at the list of xterm control sequences and scroll down until you find OSC P s; P t; ST under Operating System Controls (OSC is ESC ] and ST is ESC \).

The second case is for the screen terminal emulator, and in the list of screen control sequences, it explains that ESC _ sets screen's hardstatus (simply put, that's the title of the screen window).

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.