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I'm trying to set a little pomodoro/countdown timer for myself in the terminal.

This comment on Superuser offers a handy little shell function that will act as a countdown timer, which printfs the remaining time to STDOUT (awesome). I was thinking it would be even better if I could see the live countdown in the title of that terminal emulator tab, so I could monitor my remaining time without having to switch back and forth between tabs.

It appears the PROMPT_COMMAND environment variable can be used to update the window title, but since its contents are executed only just before Bash displays a prompt, there's no way it can live update the title while the process is running (that I know of).

Is there any way this can be done?

(It has occurred to me that I could solve this more easily by splitting a new pane in tmux, but I'm on a small screen, and I'd appreciate being able to save all the screen real estate I can.)

  • Just output the ANSI codes to stdout or stderr. Some terminals might also provide API to change their titles programmatically. – choroba Jun 22 '16 at 9:07
3

Terminal codes might be what you need, see http://wiki.bash-hackers.org/scripting/terminalcodes and https://en.wikipedia.org/wiki/ANSI_escape_code for details (or http://invisible-island.net/xterm/ctlseqs/ctlseqs.html for quite a technical description of the the codes relating to xterm).

Here an example of how to set the title:

set_title() {
  printf '\033]0;%s\007' "$*"
}
  • Holy crap you're a genius. Shame I can't upvote yet. – Ryan Lue Jun 22 '16 at 11:29
2

Just output the relevant ANSI codes to stdout or stderr.

The following works for me in an xterm:

for i in {10..1} ; do printf '\e]0;'$i'\a' ; sleep 1 ; done &

Some terminals might also provide API to change their titles programmatically.

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