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I used to know this but I forgot: I want to execute a command or a couple of commands before every single prompt. When I am in our PROD box, I want a big fat reminder above every prompt that says * YOU ARE IN PROD * and maybe another thing or two. Currently, I think that is how mail is checked but I can't remember how that configuration is set.

Using ksh and Solaris 5.10

Any idea?


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Bash has PROMPT_COMMAND, but not ksh. Couldn't you just set your warning in your PS1? –  jordanm Oct 4 '12 at 16:37
yes but that is just a static variable. let's say i want to run a command before every prompt, e.g. display the current size of my home directory (this was an arbitrary example but you get the point). –  amphibient Oct 4 '12 at 16:49
e.g. where is it specified that mail should be checked before every prompt? –  amphibient Oct 4 '12 at 16:50
I'm not a ksh user, so leaving this for someone else to answer. But this seems to work for me (updating each time the prompt is renewed): export PS1='$(date -u +%s) ${ME}:${PWD}# ' –  ire_and_curses Oct 4 '12 at 17:04
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2 Answers 2

In ksh, $PS1 is subject to command substitution and parameter expansion, so you can do things like:

function mywarning {
  tput setaf 1; tput bold
  date "+it's %T, please remember it's a production system"
  tput sgr0

PS1='$(mywarning)# '
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I'd simply put it into /etc/profile, or /etc/issue. Sometimes displaying the contents of the issue file is turned off, but I'd still think it's a good reminder.

Changing the contents of the $PS1 variable is ok, I guess, you might want to still print some warnings /etc/profile. Since it's a production system, It's ok to edit those files, since here, you want lasting changes in the system. (Normally, I'd advise against changing those files and using user files instead.)

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