Very Computer

No, not that I would know if, but in bash TMOUT exists
and has the same meaning as in ksh.

HTH,
Roberto Nibali, ratz

--

No, but there are always coding....

The below is a [bourne shell] function that puts the time in the
prompt; it uses a background process that send SIGUSR1 every so
often to the shell having a trap handler to execute this function.

I though to rewrite the function to be more pertainent to your
problem, but as I have no access to bourne shell on my FreeBSD ISP,
at least I know that _this_ works, and is applicable to the problem
with some code "massaging". Keep in mind, though, that as a user-level
process the sophisticated user can defeat this "TMOUT" emulation (as
with ksh's TMOUT, if one has not read the documentation!)

=Brian

#! /bin/echo error: only source
#*TAG:50041 2:Oct 17 1998:0644:mkprompt_sh:

# Copyright: (c) 1998
# Date: 1998/10/02
# Description: put the time in PS1 -- bourne shell version
# Name: mkprompt_sh
# Requires: autoload, mapsig, require

# Usage: mkprompt_sh
# Version: 1.01

#02
mkprompt_sh() # [-]
{       # uses global variables _prevsec and _ps1
        # define custom prompt here: $1=hours $2=minutes $3=seconds
        _force= _sleep= : ${_ps1:='[$1:$2]$ '}
        #_force= _sleep= : ${_ps1:=' [7m$1:$2$ [m '}
        test X$1 = X- && _force=ON shift
        set -- `date '+%H %M %S'`
        if test X$_force = XON -o 0${_prevsec:-60} -gt 0$3
        then    eval PS1="\"$_ps1\"" _sleep=`expr 50 - $3`
                test 0$_sleep -le 0 && _sleep=5
        else    _sleep=49       # default period
                case $3 in
                0?)     eval PS1="\"$_ps1\"" ;;
                1?)     _sleep=39 ;;
                2?)     _sleep=29 ;;
                3?)     _sleep=19 ;;
                4?)     _sleep=7 ;;
                5[0-5]) _sleep=3 ;;
                5?)     _sleep=2 ;;
                esac
        fi
        eval ${DIAG:+'echo [ mkprompt_sh: _prevsec=$3 sleeptime=$_sleep ] >&2'}
        (sleep $_sleep; kill -30 $$) </dev/null & # signal 17 = SIGUSRig
        _prevsec=$3

Quote:}

#03
cd() # [dir]

Quote:}

#04
# Warning: invoking mkprompt_sh produces the following side-effects:
#XXX use mapsig here
trap mkprompt_sh 30                     # USR1 signal subsumed for prompt
mkprompt_sh -                           # start process of time in prompt

#05 EMBEDDED MANPAGE FOR "src2man"
: '
#++
NAME
        mkprompt_sh - a mkprompt(3S) for sh(1)

SYNOPSIS

DESCRIPTION

OPTIONS

RETURN CODE

EXAMPLE

ENVIRONMENT

FILES

SEE ALSO
        mkprompt(3S)

CAVEATS
        An "alias" for the builtin "cd" is defined that uses the undocumented
        builtin "chdir" that is implemented only in sh(1), not ksh(1).

BUGS
        It is hardcoded within sh(1) that if the shell detects it is in an
        interactive environment, the PID of an invoked background process
        will be printed to /dev/tty, and thus cannot be redirected.
#--
'