tail --follow is useful to see what is being added to a file. However,
if the monitored file is followed for a certain period, it doesn't
indicate when the new content was added. It would be nice if tail
allowed to prepend timestamps to the output, as MultiTail's -ts option does.

This is a little delicate to do. The timestamp could be prepended to
each line, or only to each atomic addition to the file. Also, as we
don't know when the existing lines were added, we can't give them an
exact timestamp. MultiTail stamps them with the time of MultiTail's
launch, but I find that a bit misleading. I would consider simply not
stamping these.
In any case, as this alters the output, this should be optional.

Scanning the changelog suggests this has not been implemented as of 8.21.

Filipus Klutiero wrote:

But, but, but... multitail already does this.

As you note there is no clean solution for those previously added
lines.  No matter what is done it cannot be correct.

This is most easily done using normal tools already.  As you know the
philosophy is that programs should do one thing and then those should
work together to build more complex things.  For example here is one
way to do what you are asking.  And this is just one of many
possibilities.

  $ tail -f /var/log/syslog | perl -MPOSIX -lne 'print strftime("%T ",localtime()), $_;'

Also there already exists multitail which does what you are asking.
If so then why not simply use multitail?  Is the natural progression
that tail be mutated into multitail?  In that case we should simply
use multitail directly.  But that does have a size penalty.

  $ ll -h /usr/bin/tail /usr/bin/multitail
  -rwxr-xr-x 1 root root 264K Jan 23  2012 /usr/bin/multitail
  -rwxr-xr-x 1 root root  67K Nov 18 08:25 /usr/bin/tail

Bob

forwarded 703565 http://debbugs.gnu.org/cgi/bugreport.cgi?bug=14012
tags 703565 + upstream
thanks

Oops... reporting to 2 ITS-s at the same time is a nice feature, but I
didn't mean to try it with this case.
Anyway, as it's already done, this is also #14012 upstream.

Yes, see http://www.debian.org/Bugs/server-control#forwarded

It might have been that way, but a really long time ago. Both are
supported currently.

I apologize for the noise here. I used reportbug-ng to avoid making an
error in the pseudo-headers formatting, but instead of changing the
recipient for GNU, I added one keeping Debian. So my little trick is
uncovered!

I never intended to report this to Debian, and suggest that discussion
is kept on GNU's ITS, unless the discussion gets Debian-specific.

If the only problem with the addition was the increased size of
coreutils, I think that shouldn't be a reason to prevent the addition
for my PC (modern laptop). But Debian also targets somewhat embedded
devices. And it's far from the only distribution designed for modern
PCs. So I consider this issue as very little Debian-specific.
[...]

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