tail command does not refresh all the time

[valentin_1985]

Hello,

I am running a script with nohup and this generates a lot of logs.

In order to view the log I use tail -f nohup.out

The problem is that the info supplied by this command is not always the latest//sometimes I need to use the command again order to view the latest info added to the nohup.out file.

Can you tell me if I am doing something wrong? or this is the way it normally works?

I need to mention that I am using RedHat ES 5.0

Thanks!

[zombykillah]

Hi,
I've remmember that I had equal problems in the past with tail -f
Well I didn't use it much and decided to ignore it.

What I found, what may help you, is that tail -f will watch the file with the name at first.

Lets say you use a script to move the log sometime and start a new one.
tail -f will watch the moved file.

You may wanna try:
tail -F filename

Detailed information:
UNIX man pages : tail ()

[valentin_1985]

I do not move the nohup.out file. Simply the information it displayes is not the latest one. In order to see the latest one I have to enter the tail command again...

Any ideeas why?

[Irithori]

zombykillah is right, and here is the reason:
Apparently the filedescriptor for nohup.out gets deleted at some point.
Which is why tail cannot follow any more.

Then a new file nohup.out with a *new* filedescriptor gets created.

And yes, tail -F will follow, even if the fd has been deleted.

Just try it

tail -F /tmp/foo

echo 1 > /tmp/foo
rm -f   /tmp/foo
echo 2 > /tmp/foo

vs

 touch  /tmp/bar
tail -f /tmp/bar

echo a > /tmp/bar
rm -f /tmp/bar
echo b > /tmp/bar