ddp

#!/bin/sh
##
## Do dd(1) with progress information
## Copyright (c) 2015 SATOH Fumiyasu @ OSS Technology Corp., Japan
##
## License: GNU General Public License version 3
##

set -u

pdie() {
  echo "$0: ERROR: $1" 1>&2
  exit "${2-1}"
}

case `uname` in
Darwin|*BSD)
  dd_signal='INFO'
  ;;
*)
  dd_signal='USR1'
  ;;
esac

if [ $# -lt 1 ]; then
  echo "Usage: ${0##*/} INTERVAL [dd(1) argument ...]" 1>&2
  exit 1
fi

kicker_interval="$1"; shift
case "$kicker_interval" in
*[!0-9]*)
  pdie "Invalid interval value: $kicker_interval"
  ;;
esac

if [ "$kicker_interval" -eq 0 ]; then
  pdie "Interval value must be greater than 0"
fi

if [ -t 0 ]; then
  dd ${1+"$@"} </dev/tty &
else
  dd ${1+"$@"} &
fi
dd_pid="$!"
trap 'kill "$dd_pid" 2>/dev/null' EXIT INT

while :; do
  sleep "$kicker_interval"
  kill "-$dd_signal" "$dd_pid" 2>/dev/null || exit 0
done &
kicker_pid="$!"

wait "$dd_pid"
dd_exit="$?"

kill "$kicker_pid"

exit "$dd_exit"