Step 5: Print safely with redirect_stdout

A bar redraws its own line in place using a carriage return. A plain print() from inside the same loop writes a newline into that same spot and tears the display apart. This step adds an option that keeps the two apart.

"""Add `redirect_stdout=True` so a stray `print()` doesn't corrupt the bar.

Anything printed from inside the loop is held back and flushed above the
bar on its next redraw, instead of colliding with the bar's own carriage
return.
"""

import time

import progressbar


def main() -> None:
    widgets = [
        progressbar.Percentage(),
        ' ',
        progressbar.Bar(),
        ' ',
        progressbar.ETA(),
    ]
    with progressbar.ProgressBar(
        max_value=100, widgets=widgets, redirect_stdout=True
    ) as bar:
        for i in range(100):
            time.sleep(0.01)
            if i % 25 == 0:
                print(f'Reached step {i}')
            bar.update(i + 1)


if __name__ == '__main__':
    main()

Watch the animation: every 25 iterations the loop prints Reached step N, and that line appears above the bar as ordinary scrolled text, while the bar itself keeps redrawing cleanly on its own line underneath. Nothing is lost and nothing overwrites the bar mid-line.

The change from the previous step is one keyword argument on the constructor: redirect_stdout=True, alongside the same max_value and widgets as before – progressbar.ProgressBar(max_value=100, widgets=widgets, redirect_stdout=True). With it set, anything written to standard output while the bar is active – here, the loop’s own print(f'Reached step {i}') – is held back and flushed above the bar on its next redraw, instead of colliding with the bar’s carriage return.

That’s the whole tutorial. From here, the how-to guides cover specific tasks and the widget pages document every widget.