Problem with <> redirection to named pipe

Eric Blake
Thu Jul 19 12:43:00 GMT 2012

On 07/19/2012 12:53 AM, Nikolay Shirokovskiy wrote:
> Hello.
> When I try:
>> mkfifo fifo
>> exec 5<>fifo

POSIX says this is non-portable.  You cannot expect it to work everywhere.

> I get "Device or resource busy" error message. On linux distro these
> lines work well.

As an extension to POSIX, but not as a standard.

> I made some browising through archives and encountered notices that
> FIFOs implementation
> in Cygwin is incomplete. Is this the cause or I miss something?

I don't know if cgf's recent work on fifos has achieved the same
extension as Linux of being able to open a fifo for read-write; but I
know that Autoconf specifically avoids using <> on fifos, and instead
uses a background subshell where the two forks of the shell coordinate
which shell opens for read and the other opens for write, precisely
because of cygwin.

Eric Blake    +1-919-301-3266
Libvirt virtualization library

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