Bash – How to make the Xterm window title switch between the current running command and the current path

bashosxpromptwindow titlexterm

I want to set the Xterm window title to switch between two states:

When a command is running, show the command name (e.g. "less")
When no command is running, show the current path (e.g. "src")

I can create an Xterm window title with the current path with:

$ export PROMPT_COMMAND='echo -ne "\033]0;`basename ${PWD}`\007"'

And I can show the current running command by adding a trap statement to .bashrc:

$ trap 'echo -ne "\033]0;$BASH_COMMAND\007"' DEBUG

But I'm not able to automatically switch between the two. Is it possible?

EDIT: @terdon shows a solution that works in a regular xterm, that's cool! But I failed to mention that I use the MacOSX Terminal.app. That shows still shows "bash" instead of the current path when no command is running. With a little tinkering I figured out how to solve this.

Best Answer

You can do this if you use a function that checks whether $BASH_COMMAND is set and prints your CWD if it is not. Add these lines to your ~/.bashrc:

trap 'echo -ne "\033]0;$BASH_COMMAND\007"' DEBUG
function show_name(){ 
    if [[ -n "$BASH_COMMAND" ]]; 
    then 
    echo -en "\033]0;`pwd`\007"; 
    else 
    echo -en "\033]0;$BASH_COMMAND\007"; 
    fi 
}
export PROMPT_COMMAND='show_name'

This will cause your terminal's name to be the currently running command (if there is one) or your current directory if there is not. Bear in mind that this will result in a slightly schizophrenic terminal if you run a long loop that runs a command many times. Try it with while true; do echo foo; done for example.

If you are using zsh this is much easier to achieve (source) and it handles loops correctly:

case $TERM in
    xterm*)
      preexec () {
        print -Pn "\e]0;$*\a"
      }
    ;;
esac

Related Solutions

SSH within SSH displays the wrong machine name in the xterm title bar

Either xterm or the shell on machine_1 is configured to set the terminal title to contain the machine name. Configure your shell on machine_2 to set the terminal title to contain the machine name. You'll also want to make sure that the shell on machine_1 resets the title when the ssh session is terminated. The usual way to do this is to make the shell reset the terminal title whenever it displays a prompt. This has the added benefit of resetting the terminal title to something sensible if a full-screen text mode application sets it while it's running.

You can set the title of an xterm by displaying the escape sequence \e]2;my title here\a where \e is an escape character (\033) and \a is a bell character (\007). Include this sequence in your shell prompt. For bash, put a line like this in your ~/.bashrc:

PS1="\[\033]2;xterm on $HOSTNAME\a\]$PS1";;

The backslash-bracket punctuation \[…\] tell bash that what is inside has a width of 0 (if you leave off the brackets, the display will be garbled).

For more a fancy title that changes after each command, you can include variable and command substitutions in the prompt string if you set the promptvars option.

In zsh, set the title from the precmd function, which is executed before each prompt.

precmd () {
  print -n "\e]2;xterm on $HOSTNAME in $PWD\a"
}

While you're at it, you can set the title from preexec to contain the name of the running command. Here's a simple way which doesn't react very well to unprintable characters in the command:

preexec () {
  print -nr $'\e]2;'"xterm on $HOSTNAME running $2"$'\a'
}

Bash – How to set up `screen` to modify the window title and xterm-window title

An incomplete solution would be to modify your $PS1 prompt once inside a GNU screen. Start by modifying your shell's RC file (ie ~/.bashrc). Look for a case statement that evaluates $TERM:

case "$TERM" in
xterm*|rxvt*)
    PS1="\[\e]0;${debian_chroot:+($debian_chroot)}\u@\h: \w\a\]$PS1"
    ;;
*)
    ;;
esac

Add the following prior to the catch all (ie *)):

screen)
    PS1='\e]0;\u@\h:\w\a\ek\u@\h:\w\e\\\u@\h:\w$(__git_ps1 "(%s)")\$ '
    ;;

This will modify your hardstatus: \e]0;...\a

This will modify your window title: \ek...\e\\

The hardstatus will not show up unless you have configured it to do so. For example, you could add the following to your .screenrc:

hardstatus alwayslastline

Complex hardstatus string options will continue to work. You can substitute your now dynamic stored hardstatus for the current window using %h:

hardstatus string '%{= kw}[ %h ] %=%{w}[ %{r}%l%{w} ]%{w}[%{y} %Y-%m-%d %C %A %{w}]%{w}'

This will set the hardstatus line to the stored hardstatus between two brackets on the left side of the screen and the CPU utilization to the right along with the date and time.

Example:

 [ username@host:~ ]                    [ 0.00 0.01 0.00 ][ 2012-11-27  4:13 PM ]

CAVEATS

This will most likely break your cursor offset in your shell's history recall. (Hit your up arrow a few times, then try to edit that line. You'll see what I mean.) This is because most shells use the length for $PS1, and this will include the non-printable characters added to $PS1.
This will most likely break the xterm title bar, "freezing" it to the last status set prior to running GNU screen. What is interesting is that applications like vim that update the title bar will continue to work.
Manually setting the screen title (ie C-A A) will still work until the command prompt is updated.

Best Answer

Related Solutions

SSH within SSH displays the wrong machine name in the xterm title bar

Bash – How to set up `screen` to modify the window title and xterm-window title

Related Question