rsync silently changes special files to regular ones!

[Clemens Fischer]

* Martin Pool:

> On 25 Aug 2003 Clemens Fischer <ino-qc at spotteswoode.dnsalias.org> wrote:
>> [snip]

> You said "copy the file", so it copied the file.  Oh, you wanted *the
> contents of* the file?  You should have said so.

i did:  "rsync localhost::rsync/readme /dev/stdout" given the hype
"rsync(1) is an improved cp(1)" (which it is, no doubt about that)
should have copied that file to the screen, _to my understanding back
then_.

>> cope with device files how?
>
> RTFM please.  It can copy device nodes as device nodes, when run by
> root and given the --devices or --archive options.

i did.  the source file is a regular file, and the destination is
character special.  in this situation rsync should have told me that
the operation can't be done, unless that destination happens to allow
seeks to apply rsyncs algorithm to it.  what you are refering to is
"rsync <special file> <special file_or_dir>".

> This is the same as GNU cp.  It should not be surprising.

nonsense:

  0 p1 # cp abuse.txt /dev/stdout 
  From: clemens fischer ...

and the text appears on the screen.  but this is a freebsd-box.

>   Be aware that the destination files are replaced with a new node,
>   not updated in place.

yes, that's a good idea, but it doesn't mention special files.  even
better for idiots like me:

  Be aware that the destination files are replaced with a new node,
  not updated in place.  for example, you can't rsync a regular file
  to a special file, the destination will silently be replaced by a
  regular file.  this can also break hard links and change
  permissions.

(please check that last sentence, because rsync has special options
which change this behaviour.)

>> besides, what could be the sense in rsyncing to /dev/<whatever> as
>> destination?  does rsync handle raw magnetic tape, ZIP drives etc.?
>> rsync would at least need a device capable of [l]seek(2)s, right?
>
> Surely this is in the faq, isn't it?

well, i read the man pages and the text files in the tarball, but it
didn't jump me.  an explicit sentence is called for, and i wish it had
been in the man page.

i just checked:  a faq isn't included in the distribution tarball.  i
think you can't expect people to scan the 'net for a faq to a program
unless more information is needed than the distribution offers,
especially since i've never had any problems with rsync, neither as a
server or client.

hell, i might still be looking for the freebsd install-bug if i
wouldn't keep records of everything typed at the shell prompt (as a
memory aid).  _and_ if i had not checked that particular part of the
install-procedure.

so, in the end i simply wish that the next guy won't be hit by the
same oddity.  for this one or two sentences in the man page isn't all
that much, right?

  clemens