mirror of
https://github.com/privatevoid-net/nix-super.git
synced 2024-11-09 15:58:05 +02:00
add many more examples on escaping in strings (#10974)
This commit is contained in:
parent
3b388f6629
commit
b44909ac22
1 changed files with 114 additions and 20 deletions
|
@ -6,19 +6,60 @@
|
|||
|
||||
*Strings* can be written in three ways.
|
||||
|
||||
The most common way is to enclose the string between double quotes,
|
||||
e.g., `"foo bar"`. Strings can span multiple lines. The special
|
||||
characters `"` and `\` and the character sequence `${` must be
|
||||
escaped by prefixing them with a backslash (`\`). Newlines, carriage
|
||||
returns and tabs can be written as `\n`, `\r` and `\t`,
|
||||
respectively.
|
||||
|
||||
You can include the results of other expressions into a string by enclosing them in `${ }`, a feature known as [string interpolation].
|
||||
The most common way is to enclose the string between double quotes, e.g., `"foo bar"`.
|
||||
Strings can span multiple lines.
|
||||
The results of other expressions can be included into a string by enclosing them in `${ }`, a feature known as [string interpolation].
|
||||
|
||||
[string interpolation]: ./string-interpolation.md
|
||||
|
||||
The second way to write string literals is as an *indented string*,
|
||||
which is enclosed between pairs of *double single-quotes*, like so:
|
||||
The following must be escaped to represent them within a string, by prefixing with a backslash (`\`):
|
||||
|
||||
- Double quote (`"`)
|
||||
|
||||
> **Example**
|
||||
>
|
||||
> ```nix
|
||||
> "\""
|
||||
> ```
|
||||
>
|
||||
> "\""
|
||||
|
||||
- Backslash (`\`)
|
||||
|
||||
> **Example**
|
||||
>
|
||||
> ```nix
|
||||
> "\\"
|
||||
> ```
|
||||
>
|
||||
> "\\"
|
||||
|
||||
- Dollar sign followed by an opening curly bracket (`${`) – "dollar-curly"
|
||||
|
||||
> **Example**
|
||||
>
|
||||
> ```nix
|
||||
> "\${"
|
||||
> ```
|
||||
>
|
||||
> "\${"
|
||||
|
||||
The newline, carriage return, and tab characters can be written as `\n`, `\r` and `\t`, respectively.
|
||||
|
||||
A "double-dollar-curly" (`$${`) can be written literally.
|
||||
|
||||
> **Example**
|
||||
>
|
||||
> ```nix
|
||||
> "$${"
|
||||
> ```
|
||||
>
|
||||
> "$\${"
|
||||
|
||||
String values are output on the terminal with Nix-specific escaping.
|
||||
Strings written to files will contain the characters encoded by the escaping.
|
||||
|
||||
The second way to write string literals is as an *indented string*, which is enclosed between pairs of *double single-quotes* (`''`), like so:
|
||||
|
||||
```nix
|
||||
''
|
||||
|
@ -40,18 +81,71 @@
|
|||
"This is the first line.\nThis is the second line.\n This is the third line.\n"
|
||||
```
|
||||
|
||||
Note that the whitespace and newline following the opening `''` is
|
||||
ignored if there is no non-whitespace text on the initial line.
|
||||
> **Note**
|
||||
>
|
||||
> Whitespace and newline following the opening `''` is ignored if there is no non-whitespace text on the initial line.
|
||||
|
||||
> **Warning**
|
||||
>
|
||||
> Prefixed tab characters are not stripped.
|
||||
>
|
||||
> > **Example**
|
||||
> >
|
||||
> > The following indented string is prefixed with tabs:
|
||||
> >
|
||||
> > ''
|
||||
> > all:
|
||||
> > @echo hello
|
||||
> > ''
|
||||
> >
|
||||
> > "\tall:\n\t\t@echo hello\n"
|
||||
|
||||
Indented strings support [string interpolation].
|
||||
|
||||
Since `${` and `''` have special meaning in indented strings, you
|
||||
need a way to quote them. `$` can be escaped by prefixing it with
|
||||
`''` (that is, two single quotes), i.e., `''$`. `''` can be escaped
|
||||
by prefixing it with `'`, i.e., `'''`. `$` removes any special
|
||||
meaning from the following `$`. Linefeed, carriage-return and tab
|
||||
characters can be written as `''\n`, `''\r`, `''\t`, and `''\`
|
||||
escapes any other character.
|
||||
The following must be escaped to represent them in an indented string:
|
||||
|
||||
- `$` is escaped by prefixing it with two single quotes (`''`)
|
||||
|
||||
> **Example**
|
||||
>
|
||||
> ```nix
|
||||
> ''
|
||||
> ''$
|
||||
> ''
|
||||
> ```
|
||||
>
|
||||
> "$\n"
|
||||
|
||||
- `''` is escaped by prefixing it with one single quote (`'`)
|
||||
|
||||
> **Example**
|
||||
>
|
||||
> ```nix
|
||||
> ''
|
||||
> '''
|
||||
> ''
|
||||
> ```
|
||||
>
|
||||
> "''\n"
|
||||
|
||||
These special characters are escaped as follows:
|
||||
- Linefeed (`\n`): `''\n`
|
||||
- Carriage return (`\r`): `''\r`
|
||||
- Tab (`\t`): `''\t`
|
||||
|
||||
`''\` escapes any other character.
|
||||
|
||||
A "double-dollar-curly" (`$${`) can be written literally.
|
||||
|
||||
> **Example**
|
||||
>
|
||||
> ```nix
|
||||
> ''
|
||||
> $${
|
||||
> ''
|
||||
> ```
|
||||
>
|
||||
> "$\${\n"
|
||||
|
||||
Indented strings are primarily useful in that they allow multi-line
|
||||
string literals to follow the indentation of the enclosing Nix
|
||||
|
@ -167,7 +261,7 @@ function and the fifth being a set.
|
|||
|
||||
Note that lists are only lazy in values, and they are strict in length.
|
||||
|
||||
Elements in a list can be accessed using [`builtins.elemAt`](./builtins.md#builtins-elemAt).
|
||||
Elements in a list can be accessed using [`builtins.elemAt`](./builtins.md#builtins-elemAt).
|
||||
|
||||
## Attribute Set
|
||||
|
||||
|
|
Loading…
Reference in a new issue