Re: Probably not a bug but I was surprised: $' does not work inside "..." close.

[Dale R. Worley]

Greg Wooledge  writes:
> $'...' is a form of quoting, not an expansion.  It won't "work" inside
> of another type of quoting, just like '...' will not "work" inside "...".

Yes, that's true, and makes sense when I think about it.  But the
manual page doesn't consistently phrase it that way:

   Words of the form $'string' are treated specially.  The word expands to
   string,  ...

As you say, it isn't "expand".  And, being a quote construct, it's not a
word per se, it prevents contained characters from breaking words.

On the flip side, it doesn't look like there's a consistent word for
"the effective value of a quote construct", although "quote removal" is
used in some places.

Dale

Re: Probably not a bug but I was surprised: $' does not work inside "..." close.

[Greg Wooledge]

On Wed, Mar 17, 2021 at 09:11:48PM -0400, Dale R. Worley wrote:
> I have it encoded in my head that $ inside "..." is respected.  Subtly,
> the $'...' construction is not respected inside "...".

Bash has 5 types of quoting: '...', "...", $'...', $"..." and backslash.

$'...' is a form of quoting, not an expansion.  It won't "work" inside
of another type of quoting, just like '...' will not "work" inside "...".

echo "foo is '$foo'"

In this example, $foo is expanded, despite the fact that there are
single quotes around it, because the single quotes have no meaning in
this context.  They're inside a *different* type of quoting, so they
are just regular literal characters.

The only exception here is backslash, which retains its special powers
when inside "..." or $"...".

Probably not a bug but I was surprised: $' does not work inside "..." close.

[Dale R. Worley]

I have it encoded in my head that $ inside "..." is respected.  Subtly,
the $'...' construction is not respected inside "...".  After reading
the manual page carefully, I realized this is because the interpretation
of $'...' is not part of parameter expansion (despite its $) but rather
it is a special form of quote interpretation, "Words of the form
$'string' are treated specially."

However, I'm not sure that text is entirely accurate, either, as

$ echo xxx$'aa\ta'yyy
xxxaa   ayyy

"Word" is generally used to mean non-space characters (separted by
spaces), but the argument of "echo" is only one word, which is not, as a
whole, of the form $'...'.

Dale