Re: Fwd: Bash bug interpolating delete characters

[John Kearney]

Am 03.05.2012 15:01, schrieb Greg Wooledge:
>> Yours, Rüdiger.
>> a=x
>> del="$(echo -e "\\x7f")"
>>
>> echo "$del${a#x}" | od -ta
>> echo "$del ${a#x}" | od -ta
>> echo " $del${a#x}" | od -ta
> Yup, confirmed that it breaks here, and only when the # parameter expansion
> is included.
>
> imadev:~$ del=$'\x7f' a=x b=
> imadev:~$ echo " $del$b" | od -ta
> 0000000   sp del  nl
> 0000003
> imadev:~$ echo " $del${b}" | od -ta
> 0000000   sp del  nl
> 0000003
> imadev:~$ echo " $del${b#x}" | od -ta
> 0000000   sp del  nl
> 0000003
> imadev:~$ echo " $del${a#x}" | od -ta
> 0000000   sp  nl
> 0000002
>
> Bash 4.2.24.
>
Also Confirmed, but my output is a bit wackier.
printf %q seems to get confused, and do invalid things as well.

the \x7f becomes a \

function printTests {
    while [ $# -gt 0 ]; do
        printf    "%-20s=[%q]\n"    "${1}" "$(eval echo "${1}")"
        shift
    done
}

a=x
del=$'\x7f'
printTests '"$del${a#x}"' '"$del ${a#x}"' '" $del${a#x}"' '" $del${a%x}"'
printTests '" $del${a:0:0}"' '" $del"${a:0:0}' '" $del""${a:0:0}"'
printTests '" $del${a}"' '" $del"' '" ${del}${a:0:0}"' '"
${del:0:1}${a:0:0}"'
printTests '" ${del:0:1}${a}"' '"${del:0:1}${a#d}"' '"${del:0:1}${a#x}"'
printTests '" ${del:0:1} ${a}"' '"${del:0:1} ${a#d}"' '"${del:0:1} ${a#x}"'

output
"$del${a#x}"        =[$'\177']
"$del ${a#x}"       =[\ ]
" $del${a#x}"       =[\ ]
" $del${a%x}"       =[\ ]
" $del${a:0:0}"     =[\ ]
" $del"${a:0:0}     =[$' \177']
" $del""${a:0:0}"   =[$' \177']
" $del${a}"         =[$' \177x']
" $del"             =[$' \177']
" ${del}${a:0:0}"   =[\ ]
" ${del:0:1}${a:0:0}"=[\ ]
" ${del:0:1}${a}"   =[$' \177x']
"${del:0:1}${a#d}"  =[$'\177x']
"${del:0:1}${a#x}"  =[$'\177']
" ${del:0:1} ${a}"  =[$' \177 x']
"${del:0:1} ${a#d}" =[$'\177 x']
"${del:0:1} ${a#x}" =[\ ]