Re: [gentoo-user] Bash prompt colours

[Frank Steinmetzger]

Am Tue, Dec 07, 2021 at 10:26:11AM -0700 schrieb Grant Taylor:
> Some drive-by after-the-fact comments:
>
> On 12/6/21 4:03 PM, Frank Steinmetzger wrote:
> >      [ "$MC_SID" ] && PS1_JOBS_COUNT="${PS1_JOBS_COUNT}MC "
> >      [ "$RANGER_LEVEL" ] && PS1_JOBS_COUNT="${PS1_JOBS_COUNT}R "
>
> I've taken to using things like the following:
>
>    PS1_JOBS_COUNT="${PS1_JOBS_COUNT}${MC_SID:+MC }${RANGER_LEVEL:+R }"
>
> Leverage Bash's (and Zsh's) expansion conditional.  If the variable is set,
> then expand it to a different value.

By jove, you’re right. Maybe I’ve written that stuff before I knew about
default values. I checked in that code in September of 2016. And it could
possibly be even much older, because I clean up my config git repository
only very sporadically, as in two or three times a year.

>    ${VARIABLE:+alternate text to show if VARIABLE is set}
>
> > if [[ -z "$PROMPT_COMMAND" ]]; then
> >     PROMPT_COMMAND=__jobsprompt
> > else
> >     PROMPT_COMMAND="$PROMPT_COMMAND ; __jobsprompt"
> > fi
>
> Is there a reason to not simply do the following, eliminating the if
> conditional:
>
>    PROMPT_COMMAND=${PROMPT_COMMAND:+${PROMPT_COMMAND} ; __jobsprompt}

Maybe inexperience? :D
Or sometimes, explicit is better than implicit?

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