Mauro,
bash has more 'built-in' variables for the prompt than ksh or sh-posix. I can remember reading an article on ksh, which listed the code for a time in the PS1 pronpt. I didn't understand it. I think the next url refers to that article:
http://www.itworld.com/AppDev/1458/swol-0316-regex/Quote:
Portable shell
ksh93 is freely available for essentially all Unixes, and also, with light license restrictions, for Windows and MVS. A handful of vendors support ksh93 commercially. Korn's team at AT&T plans to upgrade a future release of KornShell with a combination of object inheritance, support for binary objects, and namespaces. Also for that release, Korn writes, "Multithreading is a possibility, but less likely than the others."
Korn has even made much of the contents of his authoritative reference book on ksh available for download. Here's an example fragment, which gives an idea of ksh's syntax and functionality:
# Set SECONDS to number of seconds since midnight.
export SECONDS="$(date '+3600*%H+60*%M+%S')"
# The following variables store hours and minutes.
typeset -Z2 _h _m # Two columns, leading zeros.
# The following expression reformats SECONDS.
_time='$((_h=(SECONDS/3600)%24)):$((_m=(SECONDS/60)%60))'
# Use _time within PS1 to get the time of day.
PS1="($_time)"'!$ '
# Note that $_time gets replaced by above expression.
# Expression gets evaluated when PS1 is displayed.
This example is particularly interesting as an example of language evolution. In 1999, after the book was published, ksh's printf operation was augmented to include new time capabilities. A consequence is that all the code above can now be abbreviated to the single line:
PS1='$(printf "(%(%H:%M)T)!$ " now)'
End Quote.
Looks similar to Steve's reply.
Hope this helps,
JP.
