Bash Multi-line Prompt/PS1 wrapping oddly

by tianon 4 years ago

GNU/Linux ◆ xterm-256color ◆ bash 2379 views

I cannot reproduce on Bash 4.4.23, but I can reproduce on all of Bash 5.0.3 (Debian’s) Bash 5.0.7 and ea578790a910fcd394930de7a1933a9ee24f9119 from the “devel” branch (“commit bash-20190705 snapshot”).

I’m on Linux and can reproduce both in my host’s install of Bash (Debian Buster), and inside containers (which is how I’ve tested various Bash versions to reproduce). I can also reproduce in all of xfce4-terminal, gnome-terminal, and terminology (in trying to make sure it really was Bash and not a quirk of the terminal). Bash in Debian is likely compiled via GCC 8.3.0, my Bash 5.0.7 was compiled via GCC 8.3.0 in Alpine 3.9, and my Bash from devel was compiled via GCC 8.3.0 in Alpine 3.10.

What I’ve found is that if PS1 contains ‘\n’ and the last line gets long enough for the cursor to be on the next line (for example, if \w gets too long), then typing will result in a single character being printed in the correct place followed by the cursor being moved to the next line.

I’ve found the simplest way to test is to have a small terminal (I use 80x24) and set PS1 to something long (and it reproduces with or without special characters, colors, or even \w, \h, \u, etc). My current testing value is PS1=’\naaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa$ ‘.

More by tianon

irssi in Docker in tmux featured 01:07

by tianon 10 years ago

"The image you are pulling has been verified" output woes 01:25

by tianon 9 years ago

docker run docker 01:20

by tianon 8 years ago

can't hax this 01:50

by tianon 10 years ago

See all

You can download this recording in asciicast v2 format, as a .cast file.

Download

Replay in terminal

You can replay the downloaded recording in your terminal using the asciinema play command:

asciinema play 257164.cast

If you don't have asciinema CLI installed then see installation instructions.

Use with stand-alone player on your website

Download asciinema player from the releases page (you only need .js and .css file), then use it like this:

<!DOCTYPE html>
<html>
<head>
  <link rel="stylesheet" type="text/css" href="asciinema-player.css" />
</head>
<body>
  <div id="player"></div>
  <script src="asciinema-player.min.js"></script>
  <script>
    AsciinemaPlayer.create(
      '/assets/257164.cast',
      document.getElementById('player'),
      { cols: 80, rows: 24 }
    );
  </script>
</body>
</html>

See asciinema player quick-start guide for full usage instructions.

While this site doesn't offer GIF conversion at the moment, you can still do it yourself with the help of asciinema GIF generator utility - agg.

Once you have it installed run the following command to create GIF file:

agg https://asciinema.org/a/257164 257164.gif

Or, if you already downloaded the recording file:

agg 257164.cast 257164.gif

Check agg --help for all available options. You can change font family and size, select color theme, adjust speed and more.

See agg manual for full usage instructions.