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1 | .\" Copyright (c) 1992, 1993 |
2 | .\" The Regents of the University of California. All rights reserved. | |
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3 | .\" All rights reserved. |
4 | .\" | |
5 | .\" This code is derived from software donated to Berkeley by | |
6 | .\" Jan-Simon Pendry and from John Heidemann of the UCLA Ficus project. | |
7 | .\" | |
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8 | .\" Redistribution and use in source and binary forms, with or without |
9 | .\" modification, are permitted provided that the following conditions | |
10 | .\" are met: | |
11 | .\" 1. Redistributions of source code must retain the above copyright | |
12 | .\" notice, this list of conditions and the following disclaimer. | |
13 | .\" 2. Redistributions in binary form must reproduce the above copyright | |
14 | .\" notice, this list of conditions and the following disclaimer in the | |
15 | .\" documentation and/or other materials provided with the distribution. | |
16 | .\" 3. All advertising materials mentioning features or use of this software | |
17 | .\" must display the following acknowledgement: | |
18 | .\" This product includes software developed by the University of | |
19 | .\" California, Berkeley and its contributors. | |
20 | .\" 4. Neither the name of the University nor the names of its contributors | |
21 | .\" may be used to endorse or promote products derived from this software | |
22 | .\" without specific prior written permission. | |
63666ef6 | 23 | .\" |
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24 | .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
25 | .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
26 | .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
27 | .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE | |
28 | .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
29 | .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |
30 | .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
31 | .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
32 | .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | |
33 | .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
34 | .\" SUCH DAMAGE. | |
5f8711c1 | 35 | .\" |
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36 | .\" @(#)mount_umap.8 8.1 (Berkeley) 6/9/93 |
37 | .\" | |
38 | .Dd "June 9, 1993" | |
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39 | .Dt MOUNT_UMAP 8 |
40 | .Os BSD 4.4 | |
41 | .Sh NAME | |
42 | .Nm mount_umap | |
43 | .Nd sample file system layer | |
44 | .Sh SYNOPSIS | |
45 | .Nm mount_umap | |
46 | .Op Fl F Ar fsoptions | |
47 | .Ar target mount-point uid-mapfile gid-mapfile | |
48 | .Sh DESCRIPTION | |
49 | The | |
50 | .Nm mount_umap | |
51 | command is used to mount a sub-tree of an existing file system | |
52 | that uses a different set of uids and gids than the local system. | |
53 | Such a file system could be mounted from a remote site via NFS or | |
54 | it could be a file system on removable media brought from some | |
5091e5f6 | 55 | foreign location that uses a different password file. |
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56 | The |
57 | .Nm mount_umap | |
58 | command uses a set of files provided by the user to make correspondences | |
59 | between uids and gids in the sub-tree's original environment and | |
60 | some other set of ids in the local environment. For instance, user | |
61 | smith might have uid 1000 in the original environment, while having | |
62 | uid 2000 in the local environment. The | |
63 | .Nm mount_umap | |
64 | command allows the subtree from smith's original environment to be | |
65 | mapped in such a way that all files with owning uid 1000 look like | |
66 | they are actually owned by uid 2000. | |
67 | .Pp | |
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68 | .Em target |
69 | should be the current location of the sub-tree in the | |
70 | local system's name space. | |
71 | .Em mount-point | |
72 | should be a directory | |
73 | where the mapped subtree is to be placed. | |
74 | .Em uid-mapfile | |
75 | and | |
76 | .Em gid-mapfile | |
77 | describe the mappings to be made between identifiers. | |
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78 | Briefly, the format of these files is a count of the number of |
79 | mappings on the first line, with each subsequent line containing | |
80 | a single mapping. Each of these mappings consists of an id from | |
81 | the original environment and the corresponding id in the local environment, | |
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82 | separated by white space. |
83 | .Em uid-mapfile | |
84 | should contain all uid | |
85 | mappings, and | |
86 | .Em gid-mapfile | |
87 | should contain all gid mappings. | |
88 | Any uids not mapped in | |
89 | .Em uid-mapfile | |
90 | will be treated as user NOBODY, | |
91 | and any gids not mapped in | |
92 | .Em gid-mapfile | |
93 | will be treated as group | |
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94 | NULLGROUP. At most 64 uids can be mapped for a given subtree, and |
95 | at most 16 groups can be mapped by a given subtree. | |
96 | .Pp | |
97 | The mapfiles can be located anywhere in the file hierarchy, but they | |
98 | must be owned by root, and they must be writable only by root. | |
99 | .Nm mount_umap | |
100 | will refuse to map the sub-tree if the ownership or permissions on | |
101 | these files are improper. It will also balk if the count of mappings | |
102 | in the first line of the map files is not correct. | |
103 | .Pp | |
104 | The layer created by the | |
105 | .Nm mount_umap | |
106 | command is meant to serve as a simple example of file system layering. | |
107 | It is not meant for production use. The implementation is not very | |
5091e5f6 | 108 | sophisticated. |
63666ef6 | 109 | .Sh SEE ALSO |
5091e5f6 | 110 | .Xr mount_null 8 , |
5f8711c1 | 111 | .Xr mount_lofs 8 |
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112 | .Sh HISTORY |
113 | The | |
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114 | .Nm mount_umap |
115 | utility first appeared in 4.4BSD. |