NAME

       umview - User Mode implementation of View-OS

SYNOPSIS

       umview [ options ] prog

DESCRIPTION

       The  main  goal  of the View-OS project is to give each process its own view of the system
       resources.  For example,  each  process  can  mount  filesystems  or  hide  some  file  or
       directories.  It  is  also  possible to assign virtual network interfaces, IP addresses or
       define virtual devices for each process (or for hierarchies of processes).
       umview is the user mode implementation of View-OS  concepts.   It  is  a  modular  partial
       virtual  machine.   umview  before loading any module is completely transparent, a process
       behaves inside umview as it  would  have  behaved  outside.   Each  module  can  customize
       specific  entities:  there  are  modules  to mount filesystems at user-level (umfuse) , to
       define virtual network interfaces (lwipv6) ,  to  define  virtual  devices  (umdev)  ,  to
       provide   interpreters   for   executables,   e.g.  to  support  executables  for  foreign
       architectures (umbinfmt) , to hide, move, overlay parts of the file system (viewfs).
       These are some examples of modules provided by the View-OS team.  umview aims to provide a
       general  interface  to  customize  the  system  call  semantics of process under specified
       conditions. So more modules will be added both by the View-OS team and by third parties.

OPTIONS

       -V name
       --viewname name
           set the name of the view. The view can be  read  and  set  using  vuname  or  viewname
           commands.
       -p module [ , module_options ]
       --preload module [ , module_options ]
           preload  modules.   Modules  will  be loaded as shared libraries thus all the rules to
           load libraries apply. Modules must be loaded from a directory within the ld.so  search
           path  or  should  be  specified  by  their  pathnames.   If  necessary  configure  the
           LD_LIBRARY_PATH  environment  variable  appropriately.   module_options   are   module
           specific  configuration  options,  thus the reader should refer to each service module
           manual for a complete description.  Modules can  be  loaded  at  run  time  using  the
           um_add_service command.
       -s
       --secure
           set kmview in human mode, i.e. force the check of capabilities and permissions. uid is
           0 at startup, in this way it is possible to load modules and mount  services.  When  a
           process  sets its uid as an unprivileged user (via setuid(2) or viewsu(1)), capability
           and permissions are enforced.
       -f rcfile
       --rc rcfile
           Use  rcfile  as  the  initialization  file  for  kmview.    kmview   always   executes
           /etc/viewosrc  if  exists,  then  kmview  executes the initialization file set by this
           option or ~/.viewosrc.
       -x
       --nonesting
           umview is able to provide module nesting, i.e. a module can provide  services  on  the
           basis of virtual services provided by another module or even by the module itself. For
           example it is possible to mount a file system image which  is  stored  in  an  already
           virtually mounted filesystem.  This feature requires the pure_libc library.  The -x or
           --nonesting option disables the nesting feature.
       -n
       --nokernelpatch
           umview is able to use some specific kernel extensions (when present) to  increase  its
           performance.  The  source  distribution  of  umview include the kernel patches for the
           latest kernels.  The kernel extensions are enabled by default  when  available.   This
           option disables the kernel extensions.
       --nokmulti
           This option disables the PTRACE_MULTI kernel extension.
       --noksysvm
           This option disables the PTRACE_SYSVM kernel extension.
       --nokviewos
           This  option disables the PTRACE_SYSVIEWOS kernel extension (already experimental, not
           yet released).
       -o file
       --output file
           This option diverts the debugging output to the file  specified,  it  is  useful  when
           umview has been compiled with debugging extensions.
       -v
       --version
           Print the version and exit.
       -h
       --help
           Print a short help message and exit.

SEE ALSO

       um_add_service(1)  um_del_service(1)  um_ls_service(1)  um_mov_service(1)  umfuse(1viewos)
       lwipv6(1viewos)   umdev(1viewos)   umbinfmt(1viewos)    viewfs(1viewos)    vuname(1viewos)
       viewname(1viewos)

AUTHORS

       View-OS  is  a  project of the Computer Science Department, University of Bologna. Project
       Leader: Renzo Davoli. Development Team: P.  Angelelli,  A.   Bacchelli,  M.  Belletti,  P.
       Beverini,  D.  Billi, A. Forni, L. Gardenghi, A. Gasparini, D. Lacamera, C. Martellini, A.
       Seraghiti <http://www.sourceforge.net/projects/view-os>

       Howto's and further information can be found on the project wiki <wiki.virtualsquare.org>.