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mount_umap(8) [netbsd man page]

MOUNT_UMAP(8)						    BSD System Manager's Manual 					     MOUNT_UMAP(8)

NAME
mount_umap -- user and group ID remapping file system layer SYNOPSIS
mount_umap [-o options] -g gid-mapfile -u uid-mapfile target mount-point DESCRIPTION
The mount_umap command is used to mount a sub-tree of an existing file system that uses a different set of uids and gids than the local sys- tem. Such a file system could be mounted from a remote site via NFS, a local file system on removable media brought from some foreign loca- tion that uses a different user/group database, or could be a local file system for another operating system which does not support Unix- style user/group IDs, or which uses a different numbering scheme. Both target and mount-point are converted to absolute paths before use. The options are as follows: -g gid-mapfile Use the group ID mapping specified in gid-mapfile. This flag is required. -o Options are specified with a -o flag followed by a comma separated string of options. See the mount(8) man page for possible options and their meanings. -u uid-mapfile Use the user ID mapping specified in uid-mapfile. This flag is required. The mount_umap command uses a set of files provided by the user to make correspondences between uids and gids in the sub-tree's original environment and some other set of ids in the local environment. For instance, user smith might have uid 1000 in the original environment, while having uid 2000 in the local environment. The mount_umap command allows the subtree from smith's original environment to be mapped in such a way that all files with owning uid 1000 look like they are actually owned by uid 2000. target should be the current location of the sub-tree in the local system's name space. mount-point should be a directory where the mapped subtree is to be placed. uid-mapfile and gid-mapfile describe the mappings to be made between identifiers. The format of the user and group ID mapping files is very simple. The first line of the file is the total number of mappings present in the file. The remaining lines each consist of two numbers: the ID in the mapped subtree and the ID in the original subtree. For example, to map uid 1000 in the original subtree to uid 2000 in the mapped subtree: 1 2000 1000 For user IDs in the original subtree for which no mapping exists, the user ID will be mapped to the user ``nobody''. For group IDs in the original subtree for which no mapping exists, the group ID will be mapped to the group ``nobody''. There is a limit of 64 user ID mappings and 16 group ID mappings. The mapfiles can be located anywhere in the file hierarchy, but they must be owned by root, and they must be writable only by root. mount_umap will refuse to map the sub-tree if the ownership or permissions on these files are improper. It will also report an error if the count of mappings in the first line of the map files is not correct. SEE ALSO
mount(8), mount_null(8) HISTORY
The mount_umap utility first appeared in 4.4BSD. BUGS
The implementation is not very sophisticated. BSD
March 6, 2001 BSD

Check Out this Related Man Page

MOUNT_FILECORE(8)					    BSD System Manager's Manual 					 MOUNT_FILECORE(8)

NAME
mount_filecore -- mount a FILECORE file system SYNOPSIS
mount_filecore [-afnR] [-g gid] [-o options] [-u uid] special node ORIGIN
The NetBSD FILECORE filesystem is a read only implementation of the filecore file system found in Acorn Computers RISC OS operating system. This operating system is the ROM based operating system found on their ARM 6, ARM7 and StrongARM 110 based RiscPC machines that are supported by the arm32 port. Under RISC OS, filecore will have multiple instantiations for file systems on different block devices such as floppies, IDE discs, SCSI discs etc. and these frequently are considered to be different filesystems e.g. ADFS, IDEFS, SCSIFS etc. DESCRIPTION
The mount_filecore command attaches the FILECORE filesystem residing on the device special to the global filesystem namespace at the location indicated by node. Both special and node are converted to absolute paths before use. This command is normally executed by mount(8) at boot time, but can be used by any user to mount a FILECORE file system on any directory that they own (provided, of course, that they have appro- priate access to the device that contains the file system). The options are as follows: -a Give all files world access. -f Append the filetype to each filename. This option currently has no effect. -g gid Set the group of the files in the file system to gid. The default group is the group of the directory on which the file system is being mounted. -n Give all files owner access. -o options Use the specified mount options, as described in mount(8). -R Give all files owner read access. -u uid Set the owner of the files in the file system to uid. The default owner is the owner of the directory on which the file system is being mounted. SEE ALSO
mount(2), unmount(2), fstab(5), mount(8) HISTORY
The mount_filecore utility first appeared in NetBSD 1.4. CAVEATS
The 'filecore' filesystem currently supports the Acorn filecore file system found on Acorn Computers RiscPC desktop machines with versions of RISC OS up to 3.70. BSD
June 25, 2004 BSD
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