Bash example to report the progress of dealing with n items that also has an estimate of time remaining.

progress.sh

#!/bin/bash
#
# Function to measure and report progress.
# A bit like PV but for general things like copying N files.
# Use it as a starting point to created your own.
#
# License: MIT Open Source
# Copyright (c) 2016 Joe Linoff

# Show the progress of N items with an estimate of the time remaining.
#   Start       The start time (date +'%s').
#   TotalItems  The total number of items.
#   CurrItem    The index of the current item. The "last" CurrItem must
#               match TotalItems for this function to be accurate.
function progress() {
    local Start=$1
    local TotalItems=$2
    local CurrItem=$3

    if (( TotalItems > 0 && CurrItem > 0 )) ; then
        local Per=$(echo "scale=4 ; ($CurrItem * 100) / $TotalItems" | bc)
        local Now=$(date +'%s')
        local Elapsed=0
        ((ElapsedTime=Now - Start))
        local TotalTime=$(echo "scale=4 ; $ElapsedTime * ($TotalItems / $CurrItem)" | bc)
        local RemainingTime=$(echo "scale=4 ; $TotalTime - $ElapsedTime" | bc)

        # Fields reported:
        #   $CurrItem       The n-th item. The $CurrItem must match $TotalItems (e.g. 1 based).
        #   $TotalItems     The total number of items.
        #   $Per            The percentage completed.
        #   $ElapsedTime    The number of seconds that have elapsed since starting.
        #   $TotalTime      An estimate of the total time required to finish.
        #   $RemainingTime  An estimate of the time remaining.
        printf '\r\033[K%6d  %6d  %5.1f%%  %d  %.1f  %.1f  ' $CurrItem $TotalItems $Per $ElapsedTime $TotalTime $RemainingTime
    fi
}

# Example: Show the progress of dealing with NumItems.
NumItems=1000
Start=$(date +'%s')
for((i=1; i<=NumItems; i++)) ; do
    progress $Start $NumItems $i
    sleep 0.02
done
printf '\n'