progressbar CLI

Installing progressbar2 installs a progressbar console script (progressbar.__main__.main()), plus bar as a shorthand for the same command in pipelines. It reads from stdin (or one or more files), writes the same bytes through to stdout (or a file), and draws a progress bar on stderr while it does – a small, Python-native reimplementation of the pv (“pipe viewer”) command. Per its own --help text it is “functional but not yet feature complete”: most flags below are wired up, but a block of pv-compatible flags is accepted for compatibility and currently has no effect. The unwired ones are listed as such below.

Worked example

curl -sL https://example.com/bigfile.iso \
    | progressbar --progress --bytes --rate > bigfile.iso

Reading from stdin means the total size isn’t known up front, so the bar falls back to a count-only display (no percentage, no bar fill) until it finishes. If you know the size in advance – from a Content-Length header, for instance – pass it explicitly so the bar can show a real percentage and ETA:

curl -sL https://example.com/bigfile.iso \
    | progressbar --progress --bytes --eta --size 128m > bigfile.iso

The bar itself always writes to stderr, so it never ends up mixed into the piped stdout data. The equivalent file-based invocation from the project README is:

progressbar --progress --timer --eta --rate --bytes input.bin -o output.bin

Positional and I/O arguments

Argument	What it does
input	One or more input file paths. Omitted or - reads stdin (the default). Multiple files are concatenated in order.
-o, --output OUTPUT	Output file path. Defaults to - (stdout).
-s, --size SIZE	Assume the total input size is SIZE instead of stat()-ing the input files (the only way to get a percentage/ETA when reading from a pipe). Accepts a plain byte count or a k/m/g/t/p suffix (powers of 1024), or @path to read another file’s size.
-l, --line-mode	Count and transfer lines instead of bytes. Input is read and written as text rather than binary.
-B, --buffer-size BYTES	Read/write in chunks of BYTES instead of the 1024-byte default. Accepts the same size suffixes as --size.

Display switches

Toggle which widgets appear. With none of these given, the bar falls back to a built-in default set (percentage/bar/timer/speed when the size is known, count/size/timer otherwise).

Flag	What it does
-p, --progress	Show the percentage and bar widgets.
-t, --timer	Show elapsed time.
-e, --eta	Show an adaptive ETA (AdaptiveETA).
-I, --fineta	Show the ETA as an absolute local time of arrival instead of a countdown.
-r, --rate	Show a transfer-speed widget.
-a, --average-rate	Also shows the transfer-speed widget. It currently selects the exact same widget as --rate: there is no separate averaging window yet, and --average-rate-window is accepted but not wired to it.
-b, --bytes	Show the running byte/line count.
-n, --numeric	Print one line per update instead of overwriting the current line (equivalent to ProgressBar(line_breaks=True) – see Terminal detection).
-q, --quiet	Suppress all progress output (uses NullBar internally).

Accepted, not yet wired up

These parse without error but have no observable effect today: -8/ --bits, -T/--buffer-percent, -A/--last-written, -F/ --format.

Output modifiers

All accepted for pv compatibility, none wired up yet: -f/--force, -c/--cursor, -W/--wait, -D/--delay-start, -0/--null, -i/--interval, -m/--average-rate-window (see --average-rate above), -w/--width, -H/--height, -N/--name.

Data transfer modifiers

Flag	What it does
-L, --rate-limit RATE	Throttle transfer to RATE bytes per second (same size suffixes as --size). Implemented by sleeping between chunks based on elapsed time vs. expected time at the target rate.

Also accepted, not wired up: -C/--no-splice, -E/--skip-errors, -Z/--error-skip-block, -S/--stop-at-size, -Y/--sync, -K/--direct-io, -X/--discard, -d/--watchfd, -R/--remote.

General options

-h/--help shows the built-in argparse help and exits. -P/--pidfile is accepted but not wired up.