Implement rupsc, clone of upsc (#5)

Fixes #4

rupsc/README.md

@@ -0,0 +1,65 @@
+# rupsc
+
+[![crates.io](https://img.shields.io/crates/v/rupsc.svg)](https://crates.io/crates/rupsc)
+[![Documentation](https://docs.rs/nut-client/badge.svg)](https://docs.rs/nut-client)
+[![MIT licensed](https://img.shields.io/crates/l/rupsc.svg)](./LICENSE)
+[![CI](https://github.com/aramperes/nut-client-rs/workflows/CI/badge.svg)](https://github.com/aramperes/nut-client-rs/actions?query=workflow%3ACI)
+
+A Rust clone of [upsc](https://networkupstools.org/docs/man/upsc.html),
+the [Network UPS Tools](https://github.com/networkupstools/nut) (NUT) demo program to display UPS variables.
+
+Written using the [nut-client](https://github.com/aramperes/nut-client-rs) crate.
+
+- Connect to `upsd`/`nut-server` using TCP
+- List UPS devices
+- List variables for a UPS device
+- Get variable value of a UPS device
+- List clients connected to a UPS device
+
+## Installation
+
+```bash
+# Using cargo
+cargo install rupsc
+
+# Or, build for other targets
+# (make sure you install the appropriate toolchain & gcc linker)
+cargo build --release --target armv7-unknown-linux-gnueabihf
+cargo build --release --target aarch64-unknown-linux-gnu
+cargo build --release --target arm-unknown-linux-gnueabihf
+```
+
+## Usage
+
+This is a clone of [`upsc`](https://networkupstools.org/docs/man/upsc.html), so the usage is the same:
+
+```bash
+# Show usage
+rupsc -h
+
+# List variables on UPS device "nutdev1" (assumes upsd running on 127.0.0.1:3493)
+rupsc nutdev1
+
+# List variables on UPS device "nutdev1" (remove upsd)
+rupsc nutdev1@192.168.1.2:3493
+
+# List available UPS devices
+rupsc -l
+
+# List available UPS devices, with description
+rupsc -L
+
+# List clients connected to UPS device "nutdev1"
+rupsc -c nutdev1
+```
+
+However, there are also some additions:
+
+```bash
+# Enable network debugging (global flag).
+ruspc -D
+```
+
+## Pronunciation
+
+> r-oopsie