> For the complete documentation index, see [llms.txt](https://freebsdfrau.gitbook.io/serious-shell-programming/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://freebsdfrau.gitbook.io/serious-shell-programming/basics/strings/double-quotes.md).

# Double-Quotes

When shell encounters a double-quote (`"`), it starts creating a string using these rules:

1. Another double-quote ends the contents but can be escapaed (e.g., `"I said, \"Hello.\""`)
2. Escape sequences **are** expanded (e.g., `\t` may be translated into a literal `TAB`)
3. Variables **are** expanded (e.g., `$foo` becomes contents of `foo` variable)
4. Command substitutions **are** performed (e.g., `$(date)` and `` `date` `` become the output of `date` command)

For example:

```
1 #!/bin/sh
2 person=Joe
3 echo "I heard from $person that \"$(date +%Y) is the year of ...,\" but I am doubtful."
```

Produces:

```
I heard from Joe that "2017 is the year of ...," but I am doubtful.
```