progress_bar.sh

#!/bin/bash

# Show a progress bar for $1 seconds
#
# Copyleft 2017 by Ignacio Nunez Hernanz <nacho _a_t_ ownyourbits _d_o_t_ com>
# GPL licensed (see end of file) * Use at your own risk!
#
# Example: progress_bar 60
#

progress_bar()
{
  local DURATION=$1
  local INT=0.25      # refresh interval

  local TIME=0
  local CURLEN=0
  local SECS=0
  local FRACTION=0

  local FB=2588       # full block

  trap "echo -e $(tput cnorm); trap - SIGINT; return" SIGINT

  echo -ne "$(tput civis)\r$(tput el)│"                # clean line

  local START=$( date +%s%N )

  while [ $SECS -lt $DURATION ]; do
    local COLS=$( tput cols )

    # main bar
    local L=$( bc -l <<< "( ( $COLS - 5 ) * $TIME  ) / ($DURATION-$INT)" | awk '{ printf "%f", $0 }' )
    local N=$( bc -l <<< $L                                              | awk '{ printf "%d", $0 }' )

    [ $FRACTION -ne 0 ] && echo -ne "$( tput cub 1 )"  # erase partial block

    if [ $N -gt $CURLEN ]; then
      for i in $( seq 1 $(( N - CURLEN )) ); do
        echo -ne \\u$FB
      done
      CURLEN=$N
    fi

    # partial block adjustment
    FRACTION=$( bc -l <<< "( $L - $N ) * 8" | awk '{ printf "%.0f", $0 }' )

    if [ $FRACTION -ne 0 ]; then 
      local PB=$( printf %x $(( 0x258F - FRACTION + 1 )) )
      echo -ne \\u$PB
    fi

    # percentage progress
    local PROGRESS=$( bc -l <<< "( 100 * $TIME ) / ($DURATION-$INT)" | awk '{ printf "%.0f", $0 }' )
    echo -ne "$( tput sc )"                            # save pos
    echo -ne "\r$( tput cuf $(( COLS - 6 )) )"         # move cur
    echo -ne "│ $PROGRESS%"
    echo -ne "$( tput rc )"                            # restore pos

    TIME=$( bc -l <<< "$TIME + $INT" | awk '{ printf "%f", $0 }' )
    SECS=$( bc -l <<<  $TIME         | awk '{ printf "%d", $0 }' )

    # take into account loop execution time
    local END=$( date +%s%N )
    local DELTA=$( bc -l <<< "$INT - ( $END - $START )/1000000000" \
                   | awk '{ if ( $0 > 0 ) printf "%f", $0; else print "0" }' )
    sleep $DELTA
    START=$( date +%s%N )
  done

  echo $(tput cnorm)
  trap - SIGINT
}

# License
#
# This script is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This script is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this script; if not, write to the
# Free Software Foundation, Inc., 59 Temple Place, Suite 330,
# Boston, MA  02111-1307  USA