This two-part patch implements the 'hexedit' command described here: http://rwmj.wordpress.com/2010/09/18/new-feature-guestfish-hexedit/#content The first part implements two new APIs for partial writing and reading of files. These are modelled after guestfs_upload and guestfs_download but allow you to specify an offset and (for download only) a size: int guestfs_download_offset (guestfs_h *g, const char *remotefilename, const char *filename, int64_t offset, int64_t size); int guestfs_upload_offset (guestfs_h *g, const char *filename, const char *remotefilename, int64_t offset); Since these calls use the streaming FileIn/FileOut part of the protocol, they are both efficient and unlimited in the amount and type of data that can be streamed. http://libguestfs.org/guestfs.3.html#functions_that_have_filein_parameters I also wrote the hexedit command using the putative hread/hwrite API and the code was much longer and more involved. Although there is an advantage to hread/hwrite which is you can read and write to and from memory. The second part of the patch implements the hexedit command itself in guestfish. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones New in Fedora 11: Fedora Windows cross-compiler. Compile Windows programs, test, and build Windows installers. Over 70 libraries supprt'd http://fedoraproject.org/wiki/MinGW http://www.annexia.org/fedora_mingw