bug#21249: "sed -i '...' -" in git head

[Jim Meyering]

On Thu, Aug 13, 2015 at 7:15 AM, Stephane Chazelas
<address@hidden> wrote:
> Hello,
>
> about this commit:
>
>> commit c033bdee411128dfebfea1974d1ee3c1d9eac572
>> Author: Jim Meyering <address@hidden>
>> Date:   Sat Jun 20 07:38:49 2015 -0700
>>
>>     sed -i: do not treat "-" as a file name
>
> the behaviour was aligned with perl's (where that syntax derives
> from).
>
> In perl, perl -pi -e 's/../../' -- *
>
> or perl -pi -e 's/../../' -- "$file"
>
> is known to be /reliable/ (work regardless of the value of $file
> (while without -i it's not, see
> https://unix.stackexchange.com/questions/170013/security-implications-of-running-perl-ne
> (-, cmd|, <file... are a problem there))
>
> That was also /safe/ in sed before that change. Treating "-" as
> stdin with -i doesn't make sense as it doesn't make sense to
> edit stdin "in-place".
>
> Now that means it breaks scripts that do:
> sed -i '...' -- "$file"
> expecting it modify $file regardless of the name of $file. Now,
> one has to do:
>
> case $file in
>  -) file=./-
> esac
> sed -i '...' -- "$file"
>
> for no good reason.
>
> IMO, that change only has negative consequences.

Thank you for the report and good argument.
I plan to revert that change with the attached patch:

0001-revert-v4.2.2-87-gc033bde-to-make-sed-i-treat-as-a-f.patch
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