John Threepwood's questions

On my host system (Windows 8 Pro 64 Bit), I installed VirtualBox (4.2.12) and installed Ubuntu 12.04 32 Bit as guest system. I also installed the VirtualBox guest utilities to create shared folders.

Now, after creating a shared folder, I added my user id to the group vboxsf, which is the owner of the shared folder with

sudo usermod -a -G vboxsf <my-user-id>

After a re-login to the Ubuntu system, I can access the shared folder and create a text file in it. But when using a text editor like gedit or Geany, I encounter a strange problem. When I try to save the file, the original file will be removed from the disk and gedit tells me

Could not save the file /media/sf_shared_folder/test.txt and

Unexpected error: Error renaming temporary file: Text file busy

Why there are conflicts when I am already in the group? And how to solve them?

# netstat -at
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address           Foreign Address         State
tcp        0      0 localhost:30037         *:*                     LISTEN
tcp        0      0 localhost:ipp           *:*                     LISTEN
tcp        0      0 *:smtp                  *:*                     LISTEN
tcp6       0      0 localhost:ipp           [::]:*                  LISTEN

What does the asterisk * in *:smtp mean ?

Why is there no IP address shown?

Often, I read something like command time(1) or printf(3) in the manpages.

What do the numbers in the brackets stand for?

This question may sound a bit stupid, but I can not really see the difference between redirection and pipes.

Redirection is used to redirect the stdout/stdin/stderr, e.g. ls > log.txt.

Pipes are used to give the output of a command as input to another command, e.g. ls | grep file.txt.

But why are there two operators for the same thing?

Why not just write ls > grep to pass the output through, isn't this just a kind of redirection also? What I am missing?