Re: Bug in tail when following files(?)

[Paul Jarc]

Peter Postmus <address@hidden> wrote:
> tail -n1 -f /var/log/messages |./festival --tts
...
> However, when the -f option is omitted, the last log entry is spoken
> completely. That's why I suspect this to be a problem in tail, not is
> Festival.

Try this:
tail -n1 -f /var/log/messages | cat

If that shows everything it should, then the problem is not in tail.
tail can't tell what's on the other side of the pipe, so it will
behave the same in both cases.  You could also run a system call trace
on it when it's piped to festival to verify that it's writing
everything it should.

> The problem arises when I connect Festival to the pipe. So that
> seems to indicate that the problem has to do with festival.

I would guess that when festival is reading from the pipe, in your
case it happens to get only part of a line, because that's all that's
been written to the pipe so far.  More data would be available if it
tried to read again, but perhaps it mistakenly thinks it has reached
EOF, since it got less data than it asked for.  Try this:
{ echo foo; sleep 3; echo bar; } | ./festival --tts
If you hear only "foo", then the bug is in festival.


paul