Ref http://www.cygwin.com/ml/cygwin/2005-04/msg00651.html

[Anders Brandén <x_anbr at hotmail dot com>]

Hi,

referring http://www.cygwin.com/ml/cygwin/2005-04/msg00651.html

I have a comment,

the problem seems to be more of a general kind(files that doesn't exist 
already don't get created for writing) as these things happen on my Cygwin 
system (running under Server 2003):

This is the new thing I've found, note that without the pipe(i.e. | cat) the 
command runs just fine:

> tar -cf /proc/self/fd/1 syntax.c | cat
> tar: /proc/self/fd/1: Cannot write: Bad file descriptor
> tar: Error is not recoverable: exiting now

and this is what happens on my system with the command referred in the link 
above, note that the error messages are the same!

> $ tar -cf >(cat) syntax.c
> tar: /proc/self/fd/63: Cannot write: Bad file descriptor
> tar: Error is not recoverable: exiting now

Both of these commands effectively creates a temporary file for both reading 
and writing and that seems to be the problem, this command runs just fine 
because I create a file for writing:

> $ tar -cf >(cat) syntax.c 63>temp

and, once created, this command runs fine too, however note that the 
redirection of input also redirects output though it really shouldn't (try 
it without having the temp file first, and then with an empty temp file and 
check the contents afterward):

> $ tar -cf >(cat) syntax.c 63<temp

So without the temp file, this fails every time:

> $ tar -cf >(cat) syntax.c 63<temp 63>temp
> bash: temp: No such file or directory

But this always works:

> $ tar -cf >(cat) syntax.c 63>temp 63<temp

Writing to temp gives >(cat temp) nothing to read:

> $ tar -cf >(cat temp) syntax.c 63>temp 63<temp

> $ tar -cf >(cat temp) syntax.c 63<temp 63>temp

However there is obviously also something wrong with the redirection of 
standard input for
> (cat) because I get no output with either of these statements even after 
> the temp file is created (writing to temp2 while attempting to read from 
> temp):

> $ tar -cf >(cat) syntax.c 63>temp2 63<temp

> $ tar -cf >(cat) syntax.c 63<temp 63>temp2

So only these gives the expected output:

> $ tar -cf >(cat temp) syntax.c 63>temp2 63<temp

> $ tar -cf >(cat temp) syntax.c 63<temp 63>temp2

Hope this helps in pinpointing the problem.


Regards,
Anders Brandén



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