ngrv

ngrv (nagare viewer, 流れビューアー) is a terminal-based tool for monitoring the progress of data through a pipeline written in Rust. It is inspired by pv(1) and can be used for similar purposes, but is not intended as a drop-in replacement for it.

Installation

From source

cargo install ngrv

From binaries

The release page contains pre-built binaries for Linux, macOS and Windows.

How to build

Please see BUILD.adoc.

Usage

Basic usage

To watch the progress of compressing a .gz file:

ngrv archive.tar | gzip > archive.tar.gz

A similar example that read a .tar archive from standard input:

cat archive.tar | ngrv -s 4GiB | gzip > archive.tar.gz

[!TIP] If any inputs are not files or the size of the file cannot be queried, the progress bar will not be shown unless -s is specified.

Generate shell completion

--generate-completion option generates shell completions to standard output.

The following shells are supported:

• bash
• elvish
• fish
• nushell
• powershell
• zsh

Example:

ngrv --generate-completion bash > ngrv.bash

Command-line options

Please see the following:

• ngrv(1)

Source code

The upstream repository is available at https://github.com/sorairolake/ngrv.git.

Changelog

Please see CHANGELOG.adoc.

Contributing

Please see CONTRIBUTING.adoc.

Acknowledgment

This program is inspired by pv.

License

Copyright (C) 2025 Shun Sakai (see AUTHORS.adoc)

1. This program is distributed under the terms of the GNU General Public License v3.0 or later.
2. Some files are distributed under the terms of the Creative Commons Attribution 4.0 International Public License.

This project is compliant with version 3.3 of the REUSE Specification. See copyright notices of individual files for more details on copyright and licensing information.