NAMEumview - User Mode implementation of View-OS
SYNOPSISumview [ options ] prog
DESCRIPTIONThe 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 networks (umnet) , 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. umview can also be used as a login shell in /etc/passwd (see passwd(5)). When umview is a login shell the mapping between each user and his/her startup script is in the file /etc/viewospasswd (see viewospasswd(5)).
OPTIONS-f script-path --rcfile script-path Load the specified startup script instead of the standard one ($(HOME)/.viewosrc). /etc/viewosrc is always loaded first, and then either $(HOME)/.viewosrc or the script specified by -fB or -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. -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. /etc/viewospasswd user startup scripts information for kmview login shells. /etc/viewosrc global configuration script $HOME/.viewosrc user configuration script (it is not automatically loaded in case of login shell. Add it at the end of the login script if needed)
SEE ALSOum_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), viewospasswd(5)
AUTHORSView-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 <//www.sourceforge.net/projects/view-os> Howto's and further information can be found on the project wiki <wiki.virtualsquare.org>. UMVIEW(1)