Re: `printf %q` but more human readable

[Peng Yu]

> It's just different quoting styles, but I prefer the single-quoted
> version too.

It is not as simple as that. See below.

> GNU /usr/bin/printf does this
>
> $ /bin/printf "$x"
> while true; do echo 'bash -i >& /dev/tcp/127.0.0.^C4444 0>&1' | bash;
> sleep 5; done &
>
> And for ${parameter@operator}
>
> $ echo "${x@Q}"
> $'while true; do echo \'bash -i >& /dev/tcp/127.0.0.^C4444 0>&1\' |
> bash;\nsleep 5; done &'

${x@Q} is not the most human-readable. For example, the extra quote is
not necessary in the following case. `printf %q` is even better in
this case. I think a most human-readable solution for all cases can
not avoiding testing the content of the string.

$ x=a; echo "${x@Q}"
'a'
$ printf %q a
a

> $ echo "${x@E}"
> while true; do echo 'bash -i >& /dev/tcp/127.0.0.^C4444 0>&1' | bash;
> sleep 5; done &

${x@Q} is not good either. It can not deal with non-print characters correctly.

$ x=$'a\001'; echo "${x@E}"
a

>
> (This confuses me since the manual stated that E produces $'' style
> escaping and Q produces single quoted escaping when used for an array...)

The above examples should clarify your confusion. My question is about
ALL cases not just about some special cases.

-- 
Regards,
Peng