Question

While taking a look at this awesome thread I noticed that some examples use

PS1="Blah Blah Blah"

and some use

PROMPT_COMMAND="Blah Blah Blah"

(and some use both) when setting the prompt in a Bash shell. What is the difference between the two? A Stack Overflow search and even a bit of broader Google searching aren’t getting me results, so even a link to the right place to look for the answer would be appreciated.

Answer 1

From the GNU Bash documentation page (Bash Reference Manual):

PROMPT_COMMAND
    If set, the value is interpreted as a command to execute before
    the printing of each primary prompt ($PS1).

I never used it, but I could have used this back when I only had sh.