Re: triviality regarding $# counts

["Mark J. Reed" <markjreed@gmail.com>]

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There still seems to be some confusion, so I'm going to back up a bit.
Apologies in advance if I tell you something you already know.

Quotes are part of the shell syntax. They aren't part of the quoted value.
If you do this:

name='Ray'


then the value stored into the variable *name* is just 3 characters: *R*,
*a*, and *y*.  There aren't any quotes anymore; they were just there long
enough to tell the shell that you want the characters in between them to be
taken literally. In this simple case, they aren't even needed; this has
exactly the same result:

name=Ray


It's important to keep the distinction in mind between the *values* you're
working with and the particular way you represent those values in the
*syntax* of the language.

Here's an example where the quotes are actually required:

multiline='hello,
there'


The above command is two physical lines of text, but only one shell
command, and that command is assigning one string value. The result is not
an array; it's a single, scalar parameter containing 12 characters, one of
which happens to be a newline:  *h*, *e*, *l*, another* l*, *o*, a comma, a
newline, *t*, *h*, *e*, *r*, and finally another *e*. You can access all of
them with subscripts; *$multiline[1]* is *h*, *$multiline[2]* is *e*, etc.
The quotes, despite being required, are still not part of the value.

The ability to do this also highlights the fact that newline is just
another character. Just like a letter of the alphabet or a digit or a
punctuation mark, it's just a number, but in the context of text that
number is interpreted as a character. The number 65 means *A*, 44 means
comma, 48 means *0*, and 10 means newline.  After the above assignment, the
newline may be found at *$multiline[7]*.

Here's another way of assigning exactly the same value to the same variable:

multiline=$'hello,\nthere'

Here we have a single-line command assigning a multiline value. The ANSI
quotes *$'*...*' *let us use the ANSI C escape sequence *\n* to mean a
newline. The result is the same: the value of *multline* is 12 characters
long, and *$multiline[7] *is a newline.

This assignment gets you something completely different:

oneline='hello,\nthere'


Now there is no newline character anywhere in the string. It's 13
characters long, not 12; *$oneline[7] *is not a newline but a backslash,
and *$oneline[8]* is an *n*.

After the above pair of assignments, you might be confused by the fact
that *echo
$multiline *and *echo $oneline* produce the same result, but that's because
*echo* is doing the same kind of translation of ANSI C escapes that the
shell does when you use *$'*...*'* quotes. If you turn that off by using *echo
-E*, then you'll get two different answers:

$ echo -E "$multiline"

hello,

there

$ echo -E "$oneline"

hello,\nthere


(I used double quotes above out of long habit; they're not strictly
necessary, especially not in zsh.)

A pair of quotes – of any variety, single, double, or ANSI – with nothing
between them represents the empty string. The empty string is nothing at
all; if you print it out by itself, it's the same as not even executing the
print command. Despite this, it is sometimes a useful thing to store in a
variable:

empty=''


After the above assignment, *$#empty* is 0. It literally contains nothing.

Again, you don't actually need the quotes; this also works:

empty=


Which reinforces the role of the quotes as syntax rather than value.

And again, an empty string is not an empty *line. *If, when you print out
the empty string, you do so with a command that adds a newline at the end,
the *output* will be an empty line, but it's the printing that makes it a
line. The value inside the variable has no line-ness.

On Sat, Apr 13, 2024 at 2:08 PM Ray Andrews <rayandrews@eastlink.ca> wrote:

> On 2024-04-13 10:27, Mark J. Reed wrote:
>
> Small followup I meant to type but didn't:
>
> On Sat, Apr 13, 2024 at 1:19 PM Mark J. Reed <markjreed@gmail.com> wrote:
>
>> redline *'\nddd=( "${(@f)aaa}" ) ... it seems like a lot of trouble to
>> copy the array as it is.'*
>>
>>
>> That comment confuses me; you aren't copying the array as it is at all!
>> You've gone from *aaa, *which has one element, to *ddd *having 8
>> elements. That's a far cry from "copying as it is".
>>
> Ah, but Mark, I figured all that out by the bottom of the post.  At that
> point I was still laboring under 'visual thinking' .  I dare say I'm
> straightened out.  I had thought that 'split on newlines' meant 'add \n's
> where needed to demarcate element boundaries'.  It's actually sorta the
> opposite -- there is no demarcation character and \n's will in fact be
> removed.  But I'm still not happy with the dollars.  I had thought that "
> $'...'  "  was grammatical but we have " ' ' "  -- meaning an empty line --
> without the leading dollar, so the closest thing I could pattern was that
> they replaced the newlines.   If anyone on the planet can get it wrong,
> it's me.
>
>
>

-- 
Mark J. Reed <markjreed@gmail.com>

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