How to add a progress bar to a shell script?

Question

When scripting in bash or any other shell in *NIX, while running a command that will take more than a few seconds, a progress bar is needed.

For example, copying a b

Answer 1

APT style progress bar (Does not break normal output)

EDIT: For an updated version check my github page

I was not satisfied with the responses on this question. What I was personally looking for was a fancy progress bar as is seen by APT.

I had a look at the C source code for APT and decided to write my own equivalent for bash.

This progress bar will stay nicely at the bottom of the terminal and will not interfere with any output sent to the terminal.

Please do note that the bar is currently fixed at 100 characters wide. If you want scale it to the size of the terminal, this is fairly easy to accomplish as well (The updated version on my github page handles this well).

I will post my script here. Usage example:

source ./progress_bar.sh
echo "This is some output"
setup_scroll_area
sleep 1
echo "This is some output 2"
draw_progress_bar 10
sleep 1
echo "This is some output 3"
draw_progress_bar 50
sleep 1
echo "This is some output 4"
draw_progress_bar 90
sleep 1
echo "This is some output 5"
destroy_scroll_area

The script (I strongly recommend the version on my github instead):

#!/bin/bash

# This code was inspired by the open source C code of the APT progress bar
# http://bazaar.launchpad.net/~ubuntu-branches/ubuntu/trusty/apt/trusty/view/head:/apt-pkg/install-progress.cc#L233

#
# Usage:
# Source this script
# setup_scroll_area
# draw_progress_bar 10
# draw_progress_bar 90
# destroy_scroll_area
#


CODE_SAVE_CURSOR="\033[s"
CODE_RESTORE_CURSOR="\033[u"
CODE_CURSOR_IN_SCROLL_AREA="\033[1A"
COLOR_FG="\e[30m"
COLOR_BG="\e[42m"
RESTORE_FG="\e[39m"
RESTORE_BG="\e[49m"

function setup_scroll_area() {
    lines=$(tput lines)
    let lines=$lines-1
    # Scroll down a bit to avoid visual glitch when the screen area shrinks by one row
    echo -en "\n"

    # Save cursor
    echo -en "$CODE_SAVE_CURSOR"
    # Set scroll region (this will place the cursor in the top left)
    echo -en "\033[0;${lines}r"

    # Restore cursor but ensure its inside the scrolling area
    echo -en "$CODE_RESTORE_CURSOR"
    echo -en "$CODE_CURSOR_IN_SCROLL_AREA"

    # Start empty progress bar
    draw_progress_bar 0
}

function destroy_scroll_area() {
    lines=$(tput lines)
    # Save cursor
    echo -en "$CODE_SAVE_CURSOR"
    # Set scroll region (this will place the cursor in the top left)
    echo -en "\033[0;${lines}r"

    # Restore cursor but ensure its inside the scrolling area
    echo -en "$CODE_RESTORE_CURSOR"
    echo -en "$CODE_CURSOR_IN_SCROLL_AREA"

    # We are done so clear the scroll bar
    clear_progress_bar

    # Scroll down a bit to avoid visual glitch when the screen area grows by one row
    echo -en "\n\n"
}

function draw_progress_bar() {
    percentage=$1
    lines=$(tput lines)
    let lines=$lines
    # Save cursor
    echo -en "$CODE_SAVE_CURSOR"

    # Move cursor position to last row
    echo -en "\033[${lines};0f"

    # Clear progress bar
    tput el

    # Draw progress bar
    print_bar_text $percentage

    # Restore cursor position
    echo -en "$CODE_RESTORE_CURSOR"
}

function clear_progress_bar() {
    lines=$(tput lines)
    let lines=$lines
    # Save cursor
    echo -en "$CODE_SAVE_CURSOR"

    # Move cursor position to last row
    echo -en "\033[${lines};0f"

    # clear progress bar
    tput el

    # Restore cursor position
    echo -en "$CODE_RESTORE_CURSOR"
}

function print_bar_text() {
    local percentage=$1

    # Prepare progress bar
    let remainder=100-$percentage
    progress_bar=$(echo -ne "["; echo -en "${COLOR_FG}${COLOR_BG}"; printf_new "#" $percentage; echo -en "${RESTORE_FG}${RESTORE_BG}"; printf_new "." $remainder; echo -ne "]");

    # Print progress bar
    if [ $1 -gt 99 ]
    then
        echo -ne "${progress_bar}"
    else
        echo -ne "${progress_bar}"
    fi
}

printf_new() {
    str=$1
    num=$2
    v=$(printf "%-${num}s" "$str")
    echo -ne "${v// /$str}"
}