# zcat - the zenoh cat

`zcat` mimics [netcat](https://sectools.org/tool/netcat/) with the difference that communication occurs via [zenoh](https://github.com/eclipse-zenoh/zenoh) instead of plain TCP or UDP.

`zcat` allows to read and write data across networks from the command line.

## Prerequisites

`zcat` is written in Rust and requires the [Rust toolchain](https://www.rust-lang.org/tools/install) to be installed on your system to build it.

## Installation

Install the `zcat` command using `cargo`. 

```sh
cargo install zcat
```

## Usage

Because `zcat` as command name is already taken by the [zcat Linux command](https://linux.die.net/man/1/zcat), this crate uses `zat` as command name.

See `zat --help` for all available options.

### Getting started

`zcat` runs in publicatoin or subscription mode when proper flags are
specified.

To read data from stdin and publish it over zenoh:

```sh
echo "Hello World" | zat -w foo/bar
```

To subscribe to data from zenoh and write it to stdout:

```sh
zat -r foo/bar
```

### QoS parameters

The QoS parameters of zenoh publications can be configured via command line.

To change the reliability:
```sh
echo "Hello World" | zat -w foo/bar -t besteffort
```

To change the reliability and the congestion control:
```sh
echo "Hello World" | zat -w foo/bar -t besteffort -d drop
```

To change the reliability, the congestion control and the priority:
```sh
echo "Hello World" | zat -w foo/bar -t besteffort -d drop -p 6
```

To change the reliability, the congestion control, the priority, and the express flag:
```sh
echo "Hello World" | zat -w foo/bar -t besteffort -d drop -p 6 -e
```

### Custom Zenoh Configuration

A zenoh configuration file can be provided in the command line.

```sh
zat --config config.json5 -w foo/bar
```

To listen for incoming connections:

```sh
zat -l tcp/127.0.0.1:6777 -w foo/bar
```

To establish a connection:

```sh
zat -e tcp/127.0.0.1:7447 -w foo/bar
```

More Zenoh options can be discovered by `zat --help`.

## License

The software is distributed with a Eclipse Public License v2.0 license. 
You can read the [license file](LICENSE.txt).