What does [%'={$percentageDone}s>%-{$percetageLeft}s] mean?

Question

I found this cool progress bar I'm using: https://stackoverflow.com/a/27147177/1480397

But I have no clue what it is doing and I'm failing to google it.

"\r\033[0G\033[2K[%'={$percentageDone}s>%-{$percetageLeft}s] -   $percentageDone%% - $absoluteDone/$absoluteTotal - avg %.4f - %s",

This is what I'm using.

I think the sequences are:

• \r - carriage return, go back to start
• \033[0G - Esc[0g Clear a tab at the current column` *
• \033[2K- Esc[2K Clear entire line *
• [%'={$percentageDone}s>%-{$percetageLeft}s]

* This doesn't do what I expect, when I remove the code, Source: http://ascii-table.com/ansi-escape-sequences-vt-100.php

So, are these sequences extracted correctly? Is the interpretation correct? And why is the last writing cool bars?

[====>                                       <much more spaces>       ]

Code to test:

for ($i = 0; $i <= 100; $i++) {
    $absoluteDone = $i;
    $absoluteTotal = 100;
    $percentageDone = floor(($absoluteDone / $absoluteTotal) * 100);
    $percetageLeft = 100 - $percentageDone;
    $avgTime = 10;
    $setCursorToLineStart = "\033[0G";
    $clearLine = "\033[2K";
    $progressbarAndStatusInfo = sprintf(
        $setCursorToLineStart
        . $clearLine
        . "[%'={$percentageDone}s>%-{$percetageLeft}s] - $percentageDone%% - $absoluteDone/$absoluteTotal - avg %.4f - %s",
        "",
        "",
        $avgTime,
        gmdate("H:i:s", $avgTime * ($absoluteTotal - $absoluteDone))
    );

    echo $progressbarAndStatusInfo;
    sleep(1);
}

Answer 1

The ansi escape codes look correct to me, however:

[%'={$percentageDone}s>%-{$percetageLeft}s]

has nothing to do with ansi. It's padding via sprintf:

'={$percentageDone}

will fill the line with x '=' chars, where x is the value in $percentageDone.

See sprintf docs for details.