Re: How is ${x:-"} parsed?

[Eli Schwartz]

On 5/9/21 4:48 PM, Peng Yu wrote:
> I see the following command is expecting something. I don't quite
> understand how it is parsed.
> 
> $ echo "${x:-"}"

$ echo "${x:-"}"}"
}

You've successfully quoted the }, even if you didn't *mean* to, now you
need to end the ${

> 
> Is the second double quote expecting another double quote to pair it?
> If so, how to pair it?
> 
> Alternatively, wouldn't it better to just print the error at the
> second double quote since it should follow the dash character?

Many programming language parsers have sub-optimal diagnostics when
tripping over a grammatical syntax error and being unable to backtrack
to the most likely place where the user made a mistake.

bash: unexpected EOF while looking for matching `}'

"unexpected EOF" while trying to find some terminating character and
searching the *entire* file for it, is a pretty common error message
here and in other languages.

The most important thing to note is that:
- a mistake was made
- the beginning of the error relates to some use of {


-- 
Eli Schwartz
Arch Linux Bug Wrangler and Trusted User

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