Voici le code (désolé pour l'indentation que le forum a mise à plat :-/ ):

#!/bin/sh
#timer.sh - chronomètre silencieux avec alarme

# Settings internals vars and temp files
SOUND="/mnt/data/Sons/alarme.wav"
export MAIN_DIALOG='
<window title="'`basename $0`'">
<vbox>
<frame Help>
<text use-markup="true">
<input file>timer.tmp</input>
</text>
</frame>
<frame Current time>
<text>
<input>date</input>
</text>
</frame>
<frame Options>
<hbox>
<checkbox>
<variable>ALARM_MODE</variable>
<label>Alarme</label>
</checkbox>
<text use-markup="true" wrap="true" width-chars="40">
<label>"<i>(countdown option is default in GUI mode).</i>"</label>
</text>
</hbox>
</frame>
<frame Parameters>
<hbox>
<text>
<label>Hours</label>
</text>
<entry max-length="2">
<variable>HOURS</variable>
</entry>
<text>
<label>Minutes</label>
</text>
<entry max-length="2">
<variable>MINUTES</variable>
</entry>
</hbox>
<text>
<label>Short message to display (you can omit this one)</label>
</text>
<entry>
<variable>ALARM_MSG</variable>
</entry>
</frame>
<hbox>
<button ok></button>
<button cancel></button>
</hbox>
</vbox>
</window>'
cat <<EOT1 >timer.tmp
Command-line usage: <b>`basename $0` [-ca] hours:minutes</b>

<u>Options</u> :
-c countdown
-a alarm
EOT1

# Help
help() {
cat <<EOT2
Usage: `basename $0` [-ca] hours:minutes
Options: -c : countdown (need time to pass)
-a : alarm (need time to reach on watch)

`basename $0` (for GUI usage w/ GTK-dialog)
EOT2
}

# Usage : countdown minutes
countdown() {
i=$1
echo " "
while [[ $i -gt 0 ]]
do
echo -e "\r "$i" minutes left \c"
sleep 60
i=$(expr $i - 1)
done
echo " - "
}

# Checking arguments
if [ $# -eq 0 ]; then
if [ -z `which gtkdialog` ]; then
help
rm -f timer.tmp
exit 0
else
VARIABLES=`gtkdialog --program=MAIN_DIALOG`
rm -f timer.tmp
eval $VARIABLES
[ "$EXIT" = "Cancel" -o "$EXIT" = "abort" ] && exit 1
fi
else
if [ "$1" = "-h" -o "$1" = "--help" ]; then
help
rm -f timer.tmp
exit 0
elif [ "$1" != "-c" -a "$1" != "-a" ]; then
echo "Error: first arg must be a '-c' or '-a' option. See help by typing \"`basename $0`\"."
rm -f timer.tmp
exit 1
else
HOURS=`echo $2 | cut -d ":" -f 1 | sed 's/^0//'`
MINUTES=`echo $2 | cut -d ":" -f 2 | sed 's/^0//'`
fi
fi
INTERVALLE_MINUTES=`echo $(( ($HOURS * 60) + $MINUTES ))`
if [ "$1" = "-a" -o $ALARM_MODE = "true" ]; then
NOW=`date | cut -d " " -f 4`
TIMEH=`echo $NOW | cut -d ":" -f 1 | sed 's/^0//'`
[ $TIMEH -gt $HOURS ] && TIMEH=`echo $(( $TIMEH - 24 ))`
TIMEM=`echo $NOW | cut -d ":" -f 2 | sed 's/^0//'`
NOW_MINUTES=`echo $(( ($TIMEH * 60) + $TIMEM ))`
INTERVALLE_MINUTES=`echo $(( $INTERVALLE_MINUTES - $NOW_MINUTES ))`
fi
echo "L'alarme sonnera dans $INTERVALLE_MINUTES minutes."
# calling countdown
countdown $INTERVALLE_MINUTES
# sound alarm
mplayer $SOUND 2>/dev/null | grep -v "."
# message if specified
shift; shift
[ -n "$*" -a -z $ALARM_MSG ] && ALARM_MSG="$*"
if [ "$ALARM_MSG" != "" ]; then
[ -n `which gtkdialog` ] && export MSG_DIALOG='<hbox><text><label>'`echo $ALARM_MSG`'</label></text></hbox>' && gtkdialog --program=MSG_DIALOG
else
echo $ALARM_MSG
fi
# final file cleaning
rm -f timer.tmp

New version: tout en ligne de commandes, plus simple, code plus structuré.

#!/bin/sh
# Timer2 - 07.12.2009
DEPENDENCIES="grep sed mplayer"
SOUND="/mnt/data/Sons/alarme.wav"
SCRIPT=`basename "$0"`
E_BADSWITCH="10 You need to use either \"-a\" or \"-c\" switch as first argument"
E_MISSINGDEPENDENCY="11 Missing dependency: "
E_NOTIME="12 No time specified"
E_NODATEIFCOUNTDOWN="13 Date must not be specified in countdown mode"
E_NOSOUND="14 No $SOUND sound file found"
E_NEGATIVETIMEOUT="15 Timeout is anterior to current time with specified date and/or time"
help()
{
echo -e "\033[1mUsage :\033[0m $SCRIPT {-a|c} [YYYY-MM-DD] HH:MM[:SS]"
echo
echo -e "\033[1mSwitches :\033[0m -a : alarm mode"
echo " -c : countdown mode"
echo "You have one and only one mandatory switch to use between these two."
echo
echo -e "\033[1mParameters :\033[0m YYYY : year (4 numbers; i.e.: 2001)"
echo " MM : month (2 numbers, 01=January, 12=December)"
echo " DD : day of the month (2 numbers; beginning with 01)"
echo " HH : hours (2 numbers; i.e.: 00=midnight)"
echo " MM : minutes (2 numbers)"
echo " SS : seconds (2 numbers)"
echo "The whole group \"YYYY-MM-DD\" and the other symbol \"SS\" are"
echo "both facultative. The \"YYYY-MM-DD\" group must not be used in"
echo "countdown mode (only hours, minutes & secondes)."
}
echo_error()
{
echo -n "Error ! " >&2
echo `echo "$*" | sed 's/^[0-9][0-9] //'` >&2
echo "Type \"$SCRIPT -h\" or \"$SCRIPT --help\" for help screen"
exit `echo "$*" | sed 's/^\([0-9][0-9]\).*$/\1/'`
}


Suite (le forum ne permet pas de poster de longs messages):


[ "$1" = "" -o "$1" = "-h" -o "$1" = "--help" ] && help && exit 0
for dep in $DEPENDENCIES; do
which "$dep" 1>/dev/null 2>&1; [ $? -ne 0 ] && echo_error "$E_MISSINGDEPENDENCY $dep"
done
[ ! -f "$SOUND" ] && echo_error "$E_NOSOUND"
[ "$1" != "-a" -a "$1" != "-c" ] && echo_error "$E_BADSWITCH"
[ "$2" = "" ] && echo_error "$E_NOTIME"
if [ "$1" = "-c" ]; then
shift
echo "$*" | grep "^[0-9][0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9]" 1>/dev/null 2>&1; [ $? -eq 0 ] && echo_error "$E_NODATEIFCOUNTDOWN"
echo "$*" | grep -E "^[0-9][0-9]:[0-9][0-9](:[0-9][0-9])?$" 1>/dev/null 2>&1; [ $? -ne 0 ] && echo_error "$E_NOTIME"
countdown_time=`echo "$*" | sed 's/0\([1-9]\)/\1/g'`
hours=`echo "$countdown_time" | cut -d ":" -f 1`
minutes=`echo "$countdown_time" | cut -d ":" -f 2`
seconds=`echo "$countdown_time" | cut -d ":" -f 3`
[ "$seconds" = "" ] && seconds=0
echo -n "Countdown"
delay_seconds=$(( ($hours * 60 + $minutes) * 60 + $seconds ))
elif [ "$1" = "-a" ]; then
shift
alarm_seconds=`date -d "$*" "+%s"`
now_seconds=`date "+%s"`
seconds=$(( ($alarm_seconds - $now_seconds) ))
minutes=0
hours=0
[ $seconds -lt 1 ] && echo_error "$E_NEGATIVETIMEOUT"
if [ $seconds -ge 60 ]; then
minutes=$(( $seconds / 60 ))
seconds=$(( $seconds % 60 ))
if [ $minutes -ge 60 ]; then
hours=$(( $minutes / 60 ))
minutes=$(( ($hours % 60) + $minutes ))
fi
fi
echo -n "Alarm"
delay_seconds=$(( ((($hours * 60) + $minutes) * 60) + $seconds ))
fi
echo " starting: timeout in $hours hours $minutes minutes $seconds seconds"
sleep $delay_seconds && mplayer "$SOUND"
exit 0



Nouvelle version plus simple (enfin j'espère), avec mode "tout console" et mode graphique, sur le modèle des utilitaires gtkdialog internes de slitaz : timer et timerbox. Par ailleurs la fonction alarme est découplée, de la même manière: alarm et alarmbox.
L'intérêt des "box" est d'avoir une interface graphique simple (pas forcément en gtkdialog, la preuve ici j'ai plutôt choisi dialog) et indépendante de la ligne de console, pour pouvoir être lancée depuis une commande graphique, par exemple en les incorporant au menu Slitaz de lxpanel. Au final les "box" ne font qu'appeler les scripts "non-box" avec certains paramètres particuliers.

Comme toujours, il faut configurer deux ou trois choses, dont le son à jouer (je ne sais pas trop pourquoi j'ai choisi de ne configurer que le son dans timer, et le son et le lecteur du son dans alarm, mais ça se trouve facilement).

Voici les code-sources respectifs:
timer:

#!/bin/sh

#scalars
SCRIPT=`basename "$0"`
HOURS=0
MINUTES=0
SECONDS=0
BEEP_LAST='false'
BEEP_DURATION=5   #seconds
BOX='false'
SOUND="/media/Elements/data/Sons/alarme.mp3"

#functions
help() {
	cat <<EOT<br />Usage : $SCRIPT [--beep] hours minutes seconds
        $SCRIPT --box
EOT
}
leadzero() {
	[ $1 -lt 10 ] && echo '0'$1 || echo $1
}

#check script parameters
[ "$1" = "" -o "$1" = "-h" -o "$1" = "--help" ] && help && exit 0
while [ $# -ne 0 ]; do
	case $1 in
		--beep )
			BEEP_LAST="true"
			shift
			;;
		--box )
			BOX="true"
			shift
			;;
		*)
			break
			;;
	esac
done

if [ "$BOX" = "true" ]; then
	TMP=$(mktemp)
	dialog --inputbox 'Hours' 8 70 2>$TMP
	[ $? -eq 0 ] && HOURS=$(cat $TMP)
	dialog --inputbox 'Minutes' 8 70 2>$TMP
	[ $? -eq 0 ] && MINUTES=$(cat $TMP)
	dialog --inputbox 'Seconds' 8 70 2>$TMP
	[ $? -eq 0 ] && SECONDS=$(cat $TMP)
	[ -f $TMP ] && rm -f $TMP
else
	HOURS=$1
	MINUTES=$2
	SECONDS=$3
fi
echo "$HOURS$MINUTES$SECONDS" | grep -q -E '^[0-9][0-9]*$'
[ $? -ne 0 ] && echo 'Error: parameters are not numbers' >&2 && exit 1
TOTAL_SECONDS=$(( HOURS * 3600 + MINUTES * 60 + SECONDS ))
[ $TOTAL_SECONDS -eq 0 ] && echo 'Error: total timer should be greater than zero' >&2 && exit 1

if [ "$BOX" = "true" ]; then
	dialog --pause "Time remaining from $(leadzero $HOURS):$(leadzero $MINUTES):$(leadzero $SECONDS)" 8 70 "$TOTAL_SECONDS"
	RET_VAL=$?
else
	echo -en "\nRemaining :\n\n\t$(leadzero $HOURS):$(leadzero $MINUTES):$(leadzero $SECONDS)"
	while [ $TOTAL_SECONDS -gt 0 ]; do
		sleep 1
		TOTAL_SECONDS=$((TOTAL_SECONDS - 1))
		S=$(( TOTAL_SECONDS % 60 ))
		TM=$(( (TOTAL_SECONDS - S) / 60 ))
		M=$(( TM % 60 ))
		H=$(( (TM - M) / 60 ))
		COUNTDOWN="$(leadzero $H):$(leadzero $M):$(leadzero $S)"
		echo -en "\r\t$COUNTDOWN"
		[ "$BEEP_LAST" = "true" -a $TOTAL_SECONDS -le $BEEP_DURATION ] && echo -en "\a"
	done
	sleep 1
	echo -e "\r\tTerminé !\n"
	RET_VAL=0
fi
[ $RET_VAL -eq 0 ] && mplayer "$SOUND" 1>/dev/null 2>&1
exit 0

timerbox

#!/bin/sh

xterm -title "Timer" -T "Timer" -geometry "70x8" -e "timer --box"

alarm

#!/bin/sh

SCRIPT=$(basename "$0")
TOMORROW="false"
BOX="false"
SOUND_COMMAND="mplayer /media/Elements/data/Sons/alarme.mp3 >/dev/null 2>&1"

help() {
	cat <<EOT<br />Usage : $SCRIPT [options] HH MM SS

Options :
    --tomorrow | -t : specify that the given time concerns the
                      next day; useful when you are late in the
                      day and wanting to set an alarm in a few
                      hours, past midnight

Parameters :
    'HH', 'MM' and 'SS' *must* be filled with their respective
    values ; add a leading zero if the number is lesser than 10
    (HH, MM and SS must have 2 numbers)
    As an example : '$SCRIPT 14 05 03'
        for an alarm at 14:05:03 in same day
EOT
}
short_help() {
	echo "Usage : $SCRIPT [-t] hours minutes seconds"
	echo "Type \"$SCRIPT -h\" or \"$SCRIPT --help\" for complete help screen"
}
err_exit() {
	echo "Error: $* !" >&2
	short_help
	exit 1
}
[ $# -eq 0 ] && short_help && exit 0
while [ $# -ne 0 ]; do
	case $1 in
		-h|--help)
			help
			exit 0
			;;
		-t|--tomorrow)
			TOMORROW="true"
			shift
			;;
		--box)
			BOX="true"
			TMP=$(mktemp)
			dialog --max-input 8 --inputbox "Alarm time (input format: HH MM SS)\n(current time is : $(date +%H:%M:%S)" 8 40 2>$TMP
			A_TIMESTRING=$(cat $TMP)
			[ -f $TMP ] && rm -f $TMP
			echo "$A_TIMESTRING" | grep -q -E '^[0-9][0-9] [0-9][0-9] [0-9][0-9]$'
			[ $? -ne 0 ] && dialog --msgbox "Error: \"$A_TIMESTRING\" is a wrong time format !" 8 70 && exit 1
			A_HOURS=$(echo $A_TIMESTRING | cut -d " " -f 1)
			A_MIN=$(echo $A_TIMESTRING | cut -d " " -f 2)
			A_SEC=$(echo $A_TIMESTRING | cut -d " " -f 3)
			break
			;;
		*)
			[ $# -ne 3 ] && err_exit "3 parameters needed"
			echo "$1$2$3" | grep -q -E '^[0-9][0-9][0-9][0-9][0-9][0-9]$'
			[ $? -ne 0 ] && err_exit "all time parameters are not 2-digit numbers"
			A_HOURS=$1
			A_MIN=$2
			A_SEC=$3
			break
			;;
	esac
done

A_TIME=$(date -d $A_HOURS:$A_MIN:$A_SEC +%s)
[ "$TOMORROW" = "true" ] && A_TIME=$(( A_TIME + 24 * 3600 ))
N_TIME=$(date +%s)
[ $A_TIME -le $N_TIME ] && err_exit "Alarm time cannot be anterior or same as current time"
D_TIME=$(( A_TIME - N_TIME ))
#D_SEC=$(( D_TIME % 60 ))
#D_MIN=$(( ((D_TIME - D_SEC) / 60) % 60 ))
#D_HOURS=$(( (D_TIME - D_MIN - D_SEC) / 3600 ))

if [ "$BOX" = "false" ]; then
	echo -e "\n\t\033[1mAlarm time\033[0m    $A_HOURS:$A_MIN:$A_SEC"
	while [ $D_TIME -ne 0 ]; do
		echo -en "\t\033[1mCurrent time\033[0m  $(date +%H:%M:%S)"
		sleep 1
		D_TIME=$(( D_TIME - 1 ))
		echo -en "\b\r"
	done
	echo -e "\t\033[1;33mTerminé !\033[0;37m                        \n"
	eval "$SOUND_COMMAND"
else
	while [ $D_TIME -ne 0 ]; do
		dialog --clear --timeout 1 --backtitle "Alarm" --msgbox "Alarm set at    : $A_HOURS:$A_MIN:$A_SEC\nCurrent time is : $(date +%H:%M:%S)" 8 40
		D_TIME=$(( D_TIME - 1 ))
	done
	eval "$SOUND_COMMAND"
	dialog --clear --msgbox "Time is out ! Alarm has finished" 8 40
fi

alarmbox

#!/bin/sh

xterm -title "Alarm" -T "Alarm" -geometry "40x8" -e "alarm --box"