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Input and output flags

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Michiel Borkent 2019-12-20 21:17:27 +01:00
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@ -219,11 +219,35 @@ Babashka supports a subset of the `ns` form where you may use `:require` and `:i
For the unsupported parts of the ns form, you may use [reader
conditionals](#reader-conditionals) to maintain compatibility with JVM Clojure.
Special vars:
### Input and output flags
- `<input>`: contains the input read from stdin. EDN by default, multiple lines of
text with the `-i` option, or multiple EDN values with the `-I` option.
- `*command-line-args*`: contain the command line args
In one-liners the `<input>` value may come in handy. It contains the input read from stdin and reads EDN by default. If you want to read in text, use the `-i` flag, which binds `<input>` to a lazy seq of lines of text. If you want to read multiple EDN values, use the `-I` flag. The `-o` option prints the result as individual lines of text. The `-O` option prints the result as lines of EDN values.
The following table illustrates the combination of options for commands of the form
echo "{{Input}}" | bb {{Input flags}} {{Output flags}} "<input>"
| Input | Input flags | Output flag | `<input>` | Output |
|----------------|-------------|-------------|---------------|----------|
| `{:a 1}` | | | `{:a 1}` | `{:a 1}` |
| hello <br> bye | `-i` | | `("hello" "bye")` | `("hello" "bye")` |
| hello <br> bye | `-i` | `-o` | `("hello" "bye")` | hello <br> bye |
| `{:a 1} {:a 2}` | `-I` | | `({:a 1} {:a 2})` | `({:a 1} {:a 2})` |
| `{:a 1}` <br> `{:a 2}` | `-I` | `-O` | `({:a 1} {:a 2})` | `{:a 1}` <br> `{:a 2}` |
When combined with the `--stream` option, the script is executed for each value in the input:
``` clojure
$ echo '{:a 1} {:a 2}' | bb --stream '<input>'
{:a 1}
{:a 2}
```
### Command-line arguments
Command-line arguments can be retrieved using `*command-line-args*`.
### Additional functions
Additionally, babashka adds the following functions: