[wplug] Linux behavior/implementation question

[Tom Rhodes]

On Thu, 31 Mar 2005 21:51:14 -0500 (EST)
Brandon Kuczenski <brandon at 301south.net> wrote:

> On Thu, 31 Mar 2005, Tom Rhodes wrote:
> 
> > On Thu, 31 Mar 2005 17:22:25 -0500
> > Eric Cooper <ecc at cmu.edu> wrote:
> >
> >> On Thu, Mar 31, 2005 at 04:56:51PM -0500, Tom Rhodes wrote:
> >>> My patch for FreeBSD (and intended patch for Sun) would make the
> >>> -r flag a synonym for -R.  This removes the code for -r, leaving
> >>> the option in tact.
> >>>
> >>> Since this is an implementation defined option, I'm guessing that
> >>> Linux works the same way and want people to prove this.
> >>
> >> cp (from GNU coreutils 5.2.1) already treats -r and -R as synonyms.
> >
> > Ok, so real Unix differentiates.  Linux does the right thing
> > here, good.
> >
> > My only worry was that the user would either:
> >
> > 1: Expect everthing, including special files to be copied when
> >   in fact they would not.
> >
> > 2: The system would hang when it encountered a special file with
> >   no indication to the user as to why.
> >
> > Thank you very much!
> >
> 
> I'm glad you found an answer to your question.
> 
> Perhaps it would be valuable or informative -- it would for me, at least 
> -- to explain what mkfifo does and why it's special?  The manual page 
> doesn't seem to be useful if you don't already know what it's talking 
> about, and web searches turn up irrelevancies or copies of the man page.

A fifo, or named pipe[1], is similar to a pipe although stored
on disk.  Mainly it is used in process comminication through
I/O streams referenced by descriptors.

mkfifo(1) is a utility provided to create these files directly.

> 
> Or if not, I'm sure it's not too important for my day-to-day activity.

It isn't.  But you did ask.

[1]: The named pipe term seen in "The Design and Implementation
     of the FreeBSD Operating System".

-- 
Tom Rhodes