[NTLUG:Discuss] Re: cpio -- echo|cpio -p (it usually takes a piped list of filenames)

[Bryan J. Smith]

On Fri, 2004-11-26 at 10:03, Fred wrote:
> I am trying to copy an encrypted file from one directory tree
> to another and cp fails with an i/o error. (yes, the file is
> ok) I thought that cpio in pass through mode would work, but
> I can't seem to get the syntax right. I am running SuSE 9.1
> pro.
> "cpio -puv  <[source filename]" 
> How do I make it work?

Try:  
  echo "[source filename]" | cpio -puv [target filename]

The passthru mode takes a _list_ of paths/filenames (pipe stdin "|"),
not actual contents (redirect stdin "<").

Two other options to consider:  
  -d  Make paths as necessary (if the source path has leading dirs)
  -m  Preserve modification time (and permissions on some platforms)


Patrick R. Michaud wrote:  
> Ummm, assuming that you did mean "cp" here,

No, by "passthru" he can only mean to use the "cpio" command.

> I can't imagine any situation where cp(1) would fail that cpio(1)
> would then be able to resolve it.

On Linux, there are only a few details "cp" don't do with recursive,
dereference and a couple of other options.  But I've still been able to
"dork it up" if I start copying socket, device and other special nodes.

In a nutshell, learning to wield find|cpio, echo|cpio, cat|cpio, etc...
is very powerful.  And it is very _universal_ across UNIX platforms.

> The cp(1) command doesn't care (or know) if the file is encrypted or
> not...as far as it's concerned, it's just a stream of bytes.

As with cpio too.

> Are you getting something more descriptive than "i/o error"?

That's a typical error for improper syntax with cpio.  Right now he's
passing the _contents_ of his redirected input (<) as various filenames.
That's why Copy I/O is barfing with an "i/o error."

> How large is the file being copied?

Yes, this could be an issue with some utilities.

> Did you try copying the file into somewhere such as /var/tmp or /tmp
> to see if that would work?
> How about copying the file into the same directory under a different
> name?

Or just check permissions on the target directory with:  
  touch [target filename]


-- 
Bryan J. Smith                                    b.j.smith at ieee.org 
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