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I was messing around with the color codes trying to understand how color code is used in bash script and I found that it works fine without including \[\] around it as in here:

This.. 

red="\033[38;5;203m"
export PS1="$red\u$green\$(__git_ps1)$blue \W"

..gives the same result as that:

red="\[\033[38;5;203m\]"
export PS1="$red\u$green\$(__git_ps1)$blue \W"

So is the second form necessary?

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  • As for "I found that it works fine without including []", I'd say you haven't really used your prompt much. Even just browsing history with arrow keys will break it. i.stack.imgur.com/VFOWn.png
    – muru
    Jul 10, 2019 at 5:30
  • It still works fine without it.. why? That's my question which still hasn't been answered.. which is why it's not a duplicate.
    – Trachyte
    Jul 10, 2019 at 5:38
  • It doesn't work fine. As I said, the prompt breaks easily.
    – muru
    Jul 10, 2019 at 5:39
  • As muru says, if you haven't seen it break, you just haven't used it heavily enough. Have you tried typing a command so long that it's longer than the window is wide, so it wraps to the next line, and then backspacing back up to the first line?
    – Scott - Слава Україні
    Jul 10, 2019 at 5:42
  • @Scott This is the clear enough answer I was looking for.. I'd say this comment should be resubmitted as an answer.. again.. the answers to the other question mentioned weren't clear enough.. neither were the previous comments here.
    – Trachyte
    Jul 10, 2019 at 5:56

1 Answer 1

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If your prompt contains non-printing characters that are not enclosed in \[...\], then the shell will miscalculate the width of the prompt.  As a result, it will be confused about where the cursor is, and it will update the display erroneously.  A classic example of this occurs if you type a command so long that it's longer than the window is wide, so it wraps to the next line, and then you backspace back up to the first line.

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