humfsify(1)



HUMFSIFY(1)                 General Commands Manual                HUMFSIFY(1)

NAME
       humfsify  --  convert a directory to the format needed by the UML humfs
       file system

SYNOPSIS
       humfsify [user]  [group]  [size]

DESCRIPTION
       This manual page documents briefly the humfsify command.

       This manual page was written  for  the  Debian  GNU/Linux  distribution
       because  the original program does not have a manual page.  Instead, it
       has documentation in HTML format; see below.

       humfsify is a Perl script necessary to convert a directory to a  format
       expected by the UML humfs file system.

HISTORY
       UMLFS  was  born  with the idea to substitute the Hostfs implementation
       with a proper one for the UML  purpose:  when  you  manage  files  with
       Hostfs within UML you need to work with two different permission layers
       (the Host one and the UML one), which have different  ideas  of  owner-
       ships.

       This  becomes evident when you need to create a file as a non-root user
       on UML: you first need to interact with the UML file system implementa-
       tion, and then with the host side.

       The  result  of  a file creation on a mounted hostfs file system is not
       what you expected: you can see that the file permissions refer  to  the
       Host side user rather than the UML creator.

       The  Host  side  user  is  to be intended as the UML instance launcher,
       meanwhile the UML side user is the one you  used  to  log  in  the  UML
       instance.

       You  can encounter a more-critical problem when creating a device node,
       operation that usually requires root privileges: you used a common user
       to  launch  the  UML  and,  since the operation is done on the Host, it
       fails, even if you logged in as root.

       Thus you need a set of tools which requires to bypass the  Hostfs  per-
       mission  checks  on  the Host side: this is done by separating the file
       permissions and the ownership from the host's files. This is  the  con-
       cept behind the HumFs and its humfsify implementation.

ARGUMENTS
       user      This  is  the user that needs to 'convert' a directory to the
                 UML file system to use UML.  This is the host user  who  will
                 be  using  this filesystem from within UML.  It may be speci-
                 fied as either a user name or a numeric user id.

       group     This is the group which your UML user belongs to.   This  may
                 be either a group name or a numeric group id

       size      This  is  the  size of the file system as seen within the UML
                 instance. It must be expressed in Gigabytes ("G"),  Megabytes
                 ("M"), or KiloBytes ("K").

EXAMPLES
       Create a directory on the host and mount it with humfsify

       host% mkdir your-humfs-dir

       host% cd humfs-dir

       Within  this  directory create a new one where you would like to have a
       UML-like hierarchy, i.e. you can loop-mount an UML rootfs

       host% mkdir dir-to-be-humsified

       host# mount -o loop rootfs /mnt

       host% cp -a /mnt dir-to-be-humsified/data

       host# humfsify user group 512M

       Then verify it on UML and mount the humfsified directory:

       UML# mount none /your-uml-host -t humfs -o

       where '/your-uml-mount-point' is the mount point on UML for the humfsi-
       fied file system, and .../dir-to-be-humfsified is the humfsified direc-
       tory in the example above. The '-t' mount  option  specifies  that  the
       file system is to be mounted as 'humfs'.

SEE ALSO
       The     HostFs     (link    to    URL    http://user-mode-linux.source-
       forge.net/new/hostfs.html)  usage  explanation  within  the  User-Mode-
       Linux Web Site

AUTHOR
       humfsify was written by Jeff Dike.

       This manual page was written by Stefano Melchior stefano.melchior@open-
       labs.it for the Debian GNU/Linux system, based on material in the Offi-
       cial User Mode Linux Web Site.

                                                                   HUMFSIFY(1)

Man(1) output converted with man2html
list of all man pages