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

[Stephane Chazelas]

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.

just my 2 cents.

-- 
Stephane