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Do not use redirection characters in your shell prompt

(tanelpoder.com)
217 points tanelpoder | 3 comments | 17 Mar 21 14:38 UTC | HN request time: 0.306s | source
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scudd ◴[17 Mar 21 15:54 UTC] No.26492906[source]▶
TIL: You can use `echo $?` to get the last process's exit code.
replies(2): >>26493051 #>>26493264 #
enriquto ◴[17 Mar 21 16:05 UTC] No.26493051[source]▶
this is actually the most useful thing to put in your prompt (much more than your username, the current directory and other redundant stuff), as in PS1='$?\$ '
replies(2): >>26495670 #>>26497266 #
chriswarbo ◴[17 Mar 21 19:17 UTC] No.26495670[source]▶
I used to leave my prompt alone until recently, but was inspired by https://news.ycombinator.com/item?id=26059023 to at least conservatively raise my expectations.

Now my prompts start with the current UNIX time, coloured red if the previous exit code was non-zero, or green if it was zero. This gives me instant feedback on success/failure, and lets me retroactively see how long a command took (without having to re-run it with `time`).

replies(1): >>26496293 #
1. enriquto ◴[17 Mar 21 20:19 UTC] No.26496293[source]▶
wouldn't it be more useful to show the time difference? Or maybe only show it in case it is larger than 1 second?
replies(2): >>26497304 #>>26500232 #
2. Izkata ◴[17 Mar 21 22:02 UTC] No.26497304[source]▶
I do that, if it's over 60 seconds - it's not as straightforward since you also need to use PROMPT_COMMAND, a debug trap, and a variable to store the start time: https://jakemccrary.com/blog/2015/05/03/put-the-last-command...
3. chriswarbo ◴[18 Mar 21 06:54 UTC] No.26500232[source]▶
Duration and start time can both be useful, and the former can be calculated from the latter as needed. Plus it's easier to implement (stateless) and has consistent alignment (always 10 digits).

BTW here's the function I use:

``` showTime() { if [[ "$?" -eq 0 ]] then TIMECOLOR='\e[92m' else TIMECOLOR='\e[91m' fi echo -e "$TIMECOLOR$(date '+%s')\e[0m" } ```