watch_dir_hashing

#! /bin/bash -

# This script estimates the current state of
# the directory hashing process.
# Usage: ./watch_dir_hashing <progress file>

trap 'exit 0' SIGUSR1
trap - PIPE INT TERM ERR HUP EXIT

minWait=5
maxWait=600
hashStartState=0
export LC_ALL=C # faster grep


procFile="$1"
fileHashes="$2"

totalHashed(){
    wc -c "$procFile" | cut -d' ' -f1
}
hashStartTime=$(date +%s)
hashStartState=$(totalHashed)

sleepUntil(){
    local now=$(date +%s)
    (( $1 > $now )) && sleep $(( $1 - $now ))
}

checkpoint=$(date +%s)
total=$( grep -va '^#\|^%' "$fileHashes" | wc -l )
waitTime=$(( $(date +%s) - $checkpoint ))
waitTime=$(( $waitTime>$minWait?$waitTime:$minWait ))
waitTime=$(( $waitTime<$maxWait?$waitTime:$maxWait ))

displayTime(){
  local T=$1
  local D=$((T/60/60/24))
  local H=$((T/60/60%24))
  local M=$((T/60%60))
  local S=$((T%60))
  (( $D > 0 )) && printf '%d days ' $D
  (( $H > 0 )) && printf '%d h ' $H
  (( $M > 0 )) && printf '%d min ' $M
  (( $D > 0 || $H > 0 || $M > 0 )) && printf 'and '
  printf '%d sec\n' $S
}
printf 'Updating progress every %s...\n' "$(displayTime $waitTime)"

finished(){
    printf '[%(%F %H:%M:%S)T] 100.00 %% (%s/%s)\n' \
        "$(date +%s)" "$total" "$total"
}
trap 'finished; exit 0' SIGUSR1
lastTime=$hashStartTime
lastState=$hashStartState
sleepUntil $(( $checkpoint + 1 ))
while true; do
    checkpoint=$(date +%s)
    current=$(totalHashed)
    CURRENT=" ($current/$total)"
    printf -v state "%02d" $(( 10000 * $current / $total ))
    STATE=" ${state:0:-2}.${state: -2} %"
    now=$(date +%s)
    if [[ $current -le $hashStartState ]]; then
        hashStartState=$current
        SPEED=""
        ETA=""
    else
        passed=$(( $now - $lastTime ))
        lastTime=$now
        diff=$(( $current - $lastState ))
        lastState=$current
        speed=$(( $diff / $passed ))
        SPEED=" at $speed files/s"
        rem=$(( $total - $current ))
        total_passed=$(( $now - $hashStartTime ))
        total_diff=$(( $current - $hashStartState ))
        eta=$(( $rem * $total_passed / $total_diff ))
        ETA=" ~ $(displayTime $eta) remaining"
    fi
    printf '[%(%F %H:%M:%S)T]%s%s%s%s\n' \
        "$now" "$STATE" "$CURRENT" "$SPEED" "$ETA"
    sleepUntil $(( $checkpoint + $waitTime ))
done