bug#49287: sed -i disrespects read-only

[Davide Brini]

On Wed, 30 Jun 2021 08:01:13 +0200, Leonid Mironov <lvm@royal.net> wrote:

>    Hello,
>
>    sed disrespects read-only file attributes when editing in place.
>
>    $ ls -l testfile*
>    -r--r--r-- 1 lvm lvm 50 Jun 30 08:32 testfile
>    $ sed 's/test/bug/g' -i~ testfile
>    $ diff testfile testfile~
>    2c2
>    < this is a bug
>    ---
>    > this is a test
>    $ sed --version
>    sed (GNU sed) 4.4

Well tecnically this is correct since sed never writes to the
original file, instead it creates a new file, writes to it and finally
renames it to the old name, so the original file permissions never come
into play (in case you're wondering: it's not really "in-place").

I agree it could be surprising, but once you know how it works behind
the scenes it should make a bit more sense.

--
D.