Re: All bash variables that can be used as temp variables?

[Dennis Williamson]

On Fri, Jan 27, 2023 at 9:33 AM Peng Yu <pengyu.ut@gmail.com> wrote:

> If you know a variable can be used (under what condition), then you
> can just list it.
>
> I only find REPLY is appropriate to be used (when 'read' is not used).
> But there may be other variables that can also be used. For example,
> probably BASH_VERSION, as I seldom need to check the bash version
> because I just use the version that works. If it has any problem with
> the version that I use, I will use another version. But there is no
> description of whether it will be changed back to its original value
> in the manual. So I don't know if I can assume so.
>
> $ echo $BASH_VERSION
> 5.1.8(1)-release
> $ BASH_VERSION=x
> $ echo $BASH_VERSION
> x
>
> Thus, just reading the manual is not sufficient. Hence, the question
> is legitimate, not as you think illegitimate.
>
> On 1/26/23, Koichi Murase <myoga.murase@gmail.com> wrote:
> > 2023年1月26日(木) 23:12 Peng Yu <pengyu.ut@gmail.com>:
> >> Yes. I have full control of the scripts that I use. I am not trying to
> >> use some other people's scripts for this purpose. So the restriction
> >> that you mentioned does not apply to me. I want to understand in this
> >> situation what variables can be used as temp variables (and under what
> >> conditions, if there are restricted conditions like in REPLY).
> >
> > There are no special Bash variables that can be used for unintended
> > purposes unconditionally. Then the condition that a variable can be
> > used as a temporary variable is theoretically that you do not use the
> > variable for the original purpose, as I have written in the previous
> > reply. The usage of each variable is described in Bash Reference
> > Manual Sec. 5.2, so you can check the description of each variable
> > there and will immediately know what would be the condition for each
> > variable. I know that you do not expect us to just copy and paste the
> > contents of Sec. 5.2 here, but then what are you expecting us for
> > replies?
> >
>
>
> --
> Regards,
> Peng
>
>
By my calculation(1) there are well over TWO HUNDRED TRILLION potential
variable names of length eight (to choose an arbitrary limit) or less in
Bash. Use any of those (or any of the very many more longer ones(2)) and
leave the (few DOZEN) built in variables alone.

Somewhere among all those X-illions are actual meaningful words and
phrases. If you find one you really like, you can reuse IT if that's what
floats your boat.

So stop. Just STOP.

1: (26 lc alpha + 26 uc alpha + underscore) * (26 lc alpha + 26 uc alpha +
10 num + underscore) ** 7

2: (adding just one more character to the length jumps the total to over 13
quadrillion)

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