Control stript which is runing in background.

[Alan Bawden]

jak <nospam at please.ty> writes:

   Il 01/01/2021 06:23, Alan Bawden ha scritto:
   > jak <nospam at please.ty> writes:
   >
   >     Running the command:
   >
   >     $ cat bible.txt > cmdpipe & cat bible.txt > cmdpipe & cat bible.txt > cmdpipe
   >
   >     the three texts do not mix....
   >
   > The three texts do not mix as long at the contents of bible.txt is short
   > enough (and provided `cat' only calls `write' once).  In the POSIX
   > specification, the manual page for the `write' system call describes
   > writing to a pipe or FIFO as follows:
   >
   >    Write requests of {PIPE_BUF} bytes or less shall not be interleaved
   >    with data from other processes doing writes on the same pipe.  Writes
   >    of greater than {PIPE_BUF} bytes may have data interleaved, on
   >    arbitrary boundaries, with writes by other processes, whether or not
   >    the O_NONBLOCK flag of the file status flags is set.
   >
   Ok. And...
        ...Running the command:

        $ cat bible.txt > cmdpipe & cat bible.txt > cmdpipe & cat bible.txt > cmdpipe

        the three texts do not mix....

Saying it again doesn't make it any more true.  If bible.txt is large
enough, they most definitely DO mix!  Just to make sure I wasn't missing
something, I tested your exact command before I sent my previous reply.
They mixed.

-- 
Alan Bawden