GNU bug report logs - #9266
tail -F does not follow through symlinks

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From: Jim Meyering <jim <at> meyering.net>
To: Bart Vanhaute <bart.vanhaute <at> gmail.com>
Cc: 9266 <at> debbugs.gnu.org
Subject: bug#9266: tail -F does not follow through symlinks
Date: Tue, 09 Aug 2011 18:28:30 +0200

Bart Vanhaute wrote:

> When I use tail -F to follow a file that is a symlink to another file,
> and that second file gets replaced, tail no longer follows the new
> file. I am not sure if this scenario is actually supported, but the
> current behaviour is unexpected to me.
>
> Detailed scenario to reproduce:
>
> in one terminal:
> $ ln -s f a
> $ touch f
> $ tail -F a
>
> in another terminal:
> $ mv f f.0
> $ echo 'hello' > f
>
> The output in terminal one will show
> tail: `a' has become inaccessible: No such file or directory
> but it will not show the 'hello' message.
>
> I am using coreutils version 8.5 on debian sid (linux kernel version
> 3.0.0), but I noticed the same behaviour in coreutils version 8.9 on
> opensuse (linux kernel version 2.6.37).

Thank you for the report.
That is indeed a difference in behavior from
the way tail works without inotify support.

If you want the old behavior (though there is no guarantee this
option will be around forever -- it's deliberately not documented),
use tail's ---disable-inotify option.  Note the three leading '-'s.

Another work-around is to use readlink to give tail
an absolute name for the file:

    tail -F "$(readlink -e a)"

Regarding tail's behavior change, we'll have to investigate
if/how to address it.

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