[SOLVED] Display progress bar in terminal tab with an ASCII OSC Sequence

Display progress bar in terminal tab with an ASCII OSC Sequence

The vte library and gnome-terminal implemented recently the presentation progress indicators. It should look like this:

See: The circle icon on left of the second tab. The progress bar within the terminal is not of interest.

The API to control terminals are ANSI escape codes. Here specifically Operating System Commands (OSC). I tried using it with bash and echo to test it:

# Set the progress bar to 50% AND wait five seconds
echo -ne "\e]9;4;1;50\a" && sleep 5

Nothing visible happens. To be sure, I opened multiple tabs and added sleep 5.

I recognized that setting the title of the terminal with

echo -en "\e]0; New TITLE\a" && sleep 5

works, but to avoid a mere brief flashing of the title, it is necessary to keep the command running for some time. Features like Control Sequence Introducers (CSI)

echo -en "\e[31m RED TEXT COLOR \e[0m DEFAULT TEXT COLOR\n"

also work. Mind the opening square bracket for CSI.

What am I doing wrong?
I'm running gnome-terminal 3.65.0 with vte 0.80.0.

Thanks :)

Other references:

// edit Thanks to egmont solved. Use ESC \ ST String terminator (Search for "String Terminator"), which requires an \e (ESC) followed by two \ (BACKSLASH), one escaping the actual following. Don't place a space between the values.

echo -ne "\e]9;4;1;75\e\\"

You need to use tabs, to see it. That makes sense, a fallback which uses the window decoration when no tabs are in use, would maybe help.

Here we see 25, 75 and 100 percent progress in gnome-terminal.

Solution

It seems to me that VTE insists that the escape sequence ends in the official ST (\e\\) rather than the nonstandard, unofficial BEL (\a).