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flagon-io/hello

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Greets people from the command line. The sample repository for g1t.

hello/README.md

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1# hello
2
3Greets people from the command line.
4
5## Usage
6
7| Argument | Description |
8| -------- | ----------- |
9| `NAME` | Optional. The name to greet. Only the first argument is read. Defaults to the `USER` environment variable, then to `world`. |
10| `--shout` | Upper-cases the greeting. |
11| `--whisper` | Lower-cases the greeting and ends it with `...` instead of `!`. With `--shout`, the last one given wins. |
12| `--reverse` | Spells the name backwards. Applies to the default name too. |
13| `--version` | Prints the crate version and exits. |
14| `--times N` | Prints the greeting `N` times. Defaults to 1. |
15| `--lang LANG` | Greets in the given language. Supported values are `en`, `es` and `fr`. Defaults to `en`. |
16| `--loud`, `-L` | Ends the greeting with `!!!` instead of `!`. |
17| `--bye` | Prints `Goodbye, NAME!` after the greeting. |
18| `--both` | Prints the greeting and `Goodbye, NAME!` on one line. |
19| `--wave` | Prints `o/` after the greeting. |
20| `--quiet` | Prints no greeting at all. `--version` still prints the version. |
21
22```sh
23$ cargo run -- Ada
24Hi, Ada!
25```
26
27```sh
28$ cargo run -- --shout Ada
29HI, ADA!
30```
31
32```sh
33$ cargo run -- --times 2 Ada
34Hi, Ada!
35Hi, Ada!
36```
37
38```sh
39$ cargo run -- --lang es Ana
40¡Hola, Ana!
41```
42
43```sh
44$ cargo run -- --lang fr Luc
45Bonjour, Luc !
46```
47
48```sh
49$ cargo run -- --version
500.1.0
51```
52
53With no arguments it greets whoever is signed in (the `USER` environment variable), or `world` if that is not set, and prints `Hi, NAME!`. Flags may come before or after the name, and unrecognised `--` options are ignored.
54
55## Examples
56
57```sh
58$ cargo run -- --shout --times 2 Ada
59HI, ADA!
60HI, ADA!
61```
62
63```sh
64$ cargo run -- --lang es --times 2 Ana
65¡Hola, Ana!
66¡Hola, Ana!
67```
68
69```sh
70$ cargo run -- --shout --lang fr Luc
71BONJOUR, LUC !
72```
73
74## Output
75
76```sh
77$ cargo run -- Grace
78Hi, Grace!
79```
80
81## Develop
82
83This project uses the Rust 2021 edition.
84
85```sh
86cargo test
87```
88
89Every pull request runs formatting, lints and tests.
90
91## Troubleshooting
92
93**`error: --times value must be a number, got "abc"`**
94
95`--times` needs a whole number of zero or more. If the value is anything else, such as `abc`, `-1` or `2.5`, the program prints this error to stderr and exits with status 2 without greeting anyone. Pass a plain number, for example `--times 3`. A `--times` with no value after it also fails, with `--times requires a value`.
96
97**The greeting says `Hi, world!` when I gave a name**
98
99An empty or whitespace-only name, such as `cargo run -- ""`, is treated as no name and the greeting uses `world`. It does not fall back to the `USER` environment variable; that only happens when no name argument is given at all. Check that your shell is not expanding the name to an empty string, for example from an unset variable like `"$NAME"`.
100
101**`error: --lang value must be one of en, es, fr, got "de"`**
102
103`--lang` only accepts `en`, `es` or `fr`. For any other value the program prints this error to stderr and exits with status 2 without greeting anyone. Pass one of the supported languages, for example `--lang es`.
104
105## License
106
107This project is licensed under the MIT License.
108The full license text is available at https://opensource.org/license/mit.