On Tue, Jan 31, 2012 at 01:29:58PM -0800, dan farmer wrote: These so-called "FileIn" and "FileOut" APIs only read and write to files. However in Linux you can easily convert this to a file descriptor, or even in-memory operation. This page describes the /dev/fd method: http://libguestfs.org/guestfs.3.html#uploading_and_downloading_to_pipes_a... Note that if you want to actively read or write from the other end of the /dev/fd file descriptor, then there has to be another process or thread involved. This is because the libguestfs API is synchronous and so the thread which makes the guestfs_* call will be doing blocking read(2) and write(2) system calls. This makes it rather hard to use /dev/fd/* from guestfish, which is single-threaded, but you can still use pipes, eg: find0 / - | <some other program> At some point you hit the limits of guestfish and it's better to use the real perl bindings, ie. Sys::Guestfs. [...] Usually better to ask libguestfs questions here: https://www.redhat.com/mailman/listinfo/libguestfs Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones virt-p2v converts physical machines to virtual machines. Boot with a live CD or over the network (PXE) and turn machines into Xen guests. http://et.redhat.com/~rjones/virt-p2v