Display a text countdown for a given number of seconds.

countdown

#!/bin/bash
#
# countdown - Display a text countdown for a given number of seconds.
#
# Chip Rosenthal
# chip@unicom.com

USAGE="usage: $0 secs"

if [[ $# -ne 1 ]] ; then
    echo "$USAGE" >&2
    exit 1
fi
nsecs="$1"
if [[ ! $nsecs =~ ^[0-9]+$ ]] ; then
    echo "$USAGE" >&2
    exit 1
fi

tnow=`date "+%s"`
tstart=$(( tnow ))
tstop=$(( tstart + nsecs ))

while (( $tnow < $tstop )) ; do
    tremain=$(( tstop - tnow ))
    echo -e "\\r${tremain} ... \\c"
    sleep 1
    tnow=`date "+%s"`
done

echo -e "\\rdone  "