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

It may be achieved in a pretty simple way:

• iterate from 0 to 100 with for loop
• sleep every step for 25ms (0.25 second)
• append to the $bar variable another = sign to make the progress bar wider
• echo progress bar and percentage (\r cleans line and returns to the beginning of the line; -ne makes echo doesn't add newline at the end and parses \r special character)

function progress {
    bar=''
    for (( x=0; x <= 100; x++ )); do
        sleep 0.25
        bar="${bar}="
        echo -ne "$bar ${x}%\r"
    done
    echo -e "\n"
}

$ progress
> ========== 10% # here: after 2.5 seconds

$ progress
> ============================== 30% # here: after 7.5 seconds

COLORED PROGRESS BAR

function progress {
    bar=''
    for (( x=0; x <= 100; x++ )); do
        sleep 0.05
        bar="${bar} "

        echo -ne "\r"
        echo -ne "\e[43m$bar\e[0m"

        local left="$(( 100 - $x ))"
        printf " %${left}s"
        echo -n "${x}%"
    done
    echo -e "\n"
}

To make a progress bar colorful, you can use formatting escape sequence - here the progress bar is yellow: \e[43m, then we reset custom settings with \e[0m, otherwise it would affect further input even when the progress bar is done.