Re: Bash' code to store string of any characters containing pair of "" and '' at once

[Budi]

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Budi reacted via Gmail
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On Sun, Dec 22, 2024 at 10:45 AM Martin D Kealey <martin@kurahaupo.gen.nz>
wrote:

>
> On Sun, 22 Dec 2024, 03:49 Budi, <budikusasi@gmail.com> wrote:
>
>> How is Bash' code to store string of any characters should be containing
>> pair of "" and '' at the same time explicitly, being exact verbatim so,
>> ie. cannot be modified, escaped or etc, as expected from ordinary/naive
>> human writing), into a variable
>>
>
> Any expectation that literal text can be written exactly verbatim (only
> adding fixed delimiters before and after) is unrealistic. We can't even do
> that in human languages, so doing that in a language intended for computers
> to read would make it very hard for humans to write.
>
> If you can abandon that assumption then Greg's answer is quite
> comprehensive.
>
> But a nagging question is why does the text contain both ' and "
> characters? Is it written in a human language or a computer language?
>
> If it's a human language, consider using “typographic” ‘quotes’ instead of
> the much-overloaded ASCII " and ' characters.
>
> If it contains shell script fragments, then consider not storing code in
> variables in the first place, but using something more appropriate such as
> functions.
>
> If it absolutely has to store shell code in variables, consider arranging
> the code in question so that it only uses one kind of quote mark, and use
> the other kind to delimit that.
>
> Failing that, by far the "simplest" approach to "literal" text is not to
> have it inside the script, but in a separate file that the script can read.
>
>  to insert \ in front of EVERY character, and NOT use any surrounding
> quotes at all. Of course, this looks REALLY ugly and hard to read, but it's
> very easy to think about when you're WRITING.
>
> Let's say you want this:
>
>  let's put "this" text worth $1 in a variable
>
> This becomes:
>
>  phrase=\l\e\t\'\s\ \p\u\t\ \"\t\h\i\s\"\ \t\e\x\t\ \w\o\r\t\h\ \$\1\
> \i\n\ \a\ \v\a\r\i\a\b\l\e
>
> If you don't mind a little bit of thinking, you can skip the \ before
> alphanumeric characters, leaving:
>
>  phrase=let\'s\ put\ \"this\"\ text\ worth\ \$1\ in\ a\ variable
>
> If you don't mind even more thinking then you can instead memorize the
> list of characters that need \ and skip all the others; they are space,
> tab, newline, and "#$'&<>*()?`\[]|
>
> Importantly \ itself is in that list. Each round of encoding will (at
> least) double the number of \ present; $foo -> \$foo -> \\\$foo ->
> \\\\\\\$foo etc.
>
>  >7 tries to no avail.. so help out solve
>>
>
> Using $( echo … ) partially undoes some of the encoding, so it's actively
> counterproductive to this task.
>
> "Guessing" when there are infinite possibilities is pointless; knowledge
> of other programming languages will lead you *away* from what you need to
> know, not towards it.
>
> You should *not* expect the code that embodies your text to look *exactly*
> like the text unless it's very simple; it will almost always need
> modifications. Stop thinking in terms of "quoting", and instead think in
> terms of "encoding".
>
> If you want to assign something to a variable, start by looking up
> "assignment" in the manual. It says that an assignment looks like
>
>  NAME=WORD
>
> The fact that NAME and WORD are upper-case is important: it means they
> have meanings that are defined elsewhere in the manual.
>
> NAME is easy: any sequence of alphanumeric characters plus underscore, as
> long as it doesn't start with a digit.
>
> WORD is more complicated, but the important point is that it *ends* just
> before the first *unquoted* whitespace or shell metacharacter. It does
> *NOT* say that it end at a "closing quote".
>
> Let me say that again, because it's critically important. The WORD that is
> assigned to the variable does *NOT* end just because there's a closing
> quote. It continues until just before whitespace or one of ();<>&|
>
> Let that sink in for a bit.
> Quotes can be opened and closed multiple times within a single WORD.
> Different parts of a single WORD can be unquoted, or quoted in one of 4
> different ways.
>
> All of this is just one assignment:
>
>  this_is_a_NAME='everything after the = is a valid WORD, and this part of
> it is in single quotes 'this-part-is-unquoted" this part is in double
> quotes"$' this part is in special quotes 'and\ the\ spaces\ in\ this\ part\
> are\ escaped\ with\ \ backslashes', which counts as a form of quoting'.
>
> -Martin
>
>>