Emulate SIGUSR1 Signal Output from DD

dd_emulator.sh

#!/bin/bash

###
# dd emulator
###

BYTES_PER_RECORD=512
BYTES_TOTAL=1020837888
BYTES_RATE=$((10*1024*1024))
BYTES_RATE_FUDGE=$((1*1024*1024))

OUTPUT_STATUS_SLEEP=1

get_microtime ()
{
  local precision=${1:-4}
  
  echo "scale=${precision}; $(date +%s%${precision}N)/(10^${precision})" | bc -l
}

get_bytes_copied ()
{
   local fudgeBytes=$(($(shuf -n 1 -i 0-$((${BYTES_RATE_FUDGE}*2)))-${BYTES_RATE_FUDGE}))
   local addBytes=$((${BYTES_RATE}+${fudgeBytes}))
   
   # Ensure returned value is multiple of BYTES_PER_RECORD
   echo $((${addBytes}-(${addBytes}%${BYTES_PER_RECORD})))
}

get_MB ()
{
  local bytes=$1
  echo "scale=0; ${bytes}/1024/1024" | bc -l
}

bytes_to_sectors ()
{
  local bytes=$1
  echo $((${bytes}/${BYTES_PER_RECORD}))
}

get_MB_persec ()
{
  local bytes=$1
  local mtime=$2
  
  echo "scale=1; ${bytes}/1024/1024/${mtime}" | bc -l
}

###
# dd SIGUSR1 output looks like this:
# 512 bytes per record
###
# 1038465+0 records in
# 1038465+0 records out
# 531694080 bytes (532 MB) copied, 11.6338 seconds, 45.7 MB/s
###

bytes_written=0
start_time=$(date +%s)
start_mtime=$(get_microtime)
while [[ ${bytes_written} -lt ${BYTES_TOTAL} ]]; do
  sleep 1
  let bytes_written+=$(get_bytes_copied)
  running_mtime=$(echo "$(get_microtime)-${start_mtime}" | bc -l)
  
  echo "$(bytes_to_sectors ${bytes_written})+0 records in" >&2
  echo "$(bytes_to_sectors ${bytes_written})+0 records out" >&2
  echo "${bytes_written} bytes ($(get_MB ${bytes_written}) MB) copied, ${running_mtime}, $(get_MB_persec ${bytes_written} ${running_mtime}) MB/s" >&2
done