yaml: multi-line

yaml/README.md

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+# YAML
+
+## 1. Write multiple-line string
+
+Source:
+
+- <https://stackoverflow.com/questions/3790454/how-do-i-break-a-string-in-yaml-over-multiple-lines>
+- <https://yaml-multiline.info/>
+
+There are two types of formats that YAML supports for strings: _block scalar_ and _flow scalar_ formats.
+
+### 1.1. Block scalar
+
+A block scalar header has three parts:
+
+- **Block Style Indicator**: The [block style](https://yaml.org/spec/1.2.2/#812-literal-style) indicates how newlines inside the block should behave. If you would like them to be kept as newlines, use the **literal** style, indicated by a pipe (`|`). If instead you want them to be replaced by spaces, use the **folded** style, indicated by a right angle bracket (`>`). (To get a newline using the folded style, leave a blank line by putting two newlines in. Lines with extra indentation are also not folded.)
+
+- **Block Chomping Indicator**: The [chomping indicator](https://yaml.org/spec/1.2.2/#8112-block-chomping-indicator) controls what should happen with newlines at the end of the string. The default, **clip**, puts a single newline at the end of the string. To remove all newlines, strip them by putting a minus sign (`-`) after the style indicator. Both clip and strip ignore how many newlines are actually at the end of the block; to **keep** them all put a plus sign (`+`) after the style indicator.
+
+- **Indentation Indicator**: Ordinarily, the number of spaces you're using to indent a block will be automatically guessed from its first line. You may need a [block indentation indicator](https://yaml.org/spec/1.2.2/#8111-block-indentation-indicator) if the first line of the block starts with extra spaces. In this case, simply put the number of spaces used for indentation (between 1 and 9) at the end of the header.
+
+### 1.2. Flow scalar
+
+- Single-quoted:
+
+```yaml
+example: 'Several lines of text,\n
+··containing ''single quotes''. Escapes (like \n) don''t do anything.\n
+··\n
+··Newlines can be added by leaving a blank line.\n
+····Leading whitespace on lines is ignored.'\n
+```
+
+- Double-quoted:
+
+```yaml
+example: "Several lines of text,\n
+··containing \"double quotes\". Escapes (like \\n) work.\nIn addition,\n
+··newlines can be esc\\n
+··aped to prevent them from being converted to a space.\n
+··\n
+··Newlines can also be added by leaving a blank line.\n
+····Leading whitespace on lines is ignored."\n
+```
+
+- Plain:
+
+```yaml
+example: Several lines of text,\n
+··with some "quotes" of various 'types'.\n
+··Escapes (like \n) don't do anything.\n
+··\n
+··Newlines can be added by leaving a blank line.\n
+····Additional leading whitespace is ignored.\n
+```