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1 | .\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com> |
2 | .\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com> | |
3 | .\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org> | |
4 | .\" | |
5 | .\" SPDX-License-Identifier: GPL-3.0-or-later | |
6 | .\" | |
7 | .TH proc_pid_mountinfo 5 (date) "Linux man-pages (unreleased)" | |
8 | .SH NAME | |
9 | /proc/pid/mountinfo \- mounts informations | |
10 | .SH DESCRIPTION | |
11 | .TP | |
12 | .IR /proc/ pid /mountinfo " (since Linux 2.6.26)" | |
13 | .\" This info adapted from Documentation/filesystems/proc.txt | |
14 | .\" commit 2d4d4864ac08caff5c204a752bd004eed4f08760 | |
15 | This file contains information about mounts | |
16 | in the process's mount namespace (see | |
17 | .BR mount_namespaces (7)). | |
18 | It supplies various information | |
19 | (e.g., propagation state, root of mount for bind mounts, | |
20 | identifier for each mount and its parent) that is missing from the (older) | |
21 | .IR /proc/ pid /mounts | |
22 | file, and fixes various other problems with that file | |
23 | (e.g., nonextensibility, | |
24 | failure to distinguish per-mount versus per-superblock options). | |
25 | .IP | |
26 | The file contains lines of the form: | |
27 | .IP | |
28 | .EX | |
29 | 36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 \- ext3 /dev/root rw,errors=continue | |
30 | (1)(2)(3) (4) (5) (6) (7) (8) (9) (10) (11) | |
31 | .EE | |
32 | .IP | |
33 | The numbers in parentheses are labels for the descriptions below: | |
34 | .RS 7 | |
35 | .TP 5 | |
36 | (1) | |
37 | mount ID: a unique ID for the mount (may be reused after | |
38 | .BR umount (2)). | |
39 | .TP | |
40 | (2) | |
41 | parent ID: the ID of the parent mount | |
42 | (or of self for the root of this mount namespace's mount tree). | |
43 | .IP | |
44 | If a new mount is stacked on top of a previous existing mount | |
45 | (so that it hides the existing mount) at pathname P, | |
46 | then the parent of the new mount is the previous mount at that location. | |
47 | Thus, when looking at all the mounts stacked at a particular location, | |
48 | the top-most mount is the one that is not the parent | |
49 | of any other mount at the same location. | |
50 | (Note, however, that this top-most mount will be accessible only if | |
51 | the longest path subprefix of P that is a mount point | |
52 | is not itself hidden by a stacked mount.) | |
53 | .IP | |
54 | If the parent mount lies outside the process's root directory (see | |
55 | .BR chroot (2)), | |
56 | the ID shown here won't have a corresponding record in | |
57 | .I mountinfo | |
58 | whose mount ID (field 1) matches this parent mount ID | |
59 | (because mounts that lie outside the process's root directory | |
60 | are not shown in | |
61 | .IR mountinfo ). | |
62 | As a special case of this point, | |
63 | the process's root mount may have a parent mount | |
64 | (for the initramfs filesystem) that lies | |
65 | .\" Miklos Szeredi, Nov 2017: The hidden one is the initramfs, I believe | |
66 | .\" mtk: In the initial mount namespace, this hidden ID has the value 0 | |
67 | outside the process's root directory, | |
68 | and an entry for that mount will not appear in | |
69 | .IR mountinfo . | |
70 | .TP | |
71 | (3) | |
72 | major:minor: the value of | |
73 | .I st_dev | |
74 | for files on this filesystem (see | |
75 | .BR stat (2)). | |
76 | .TP | |
77 | (4) | |
78 | root: the pathname of the directory in the filesystem | |
79 | which forms the root of this mount. | |
80 | .TP | |
81 | (5) | |
82 | mount point: the pathname of the mount point relative | |
83 | to the process's root directory. | |
84 | .TP | |
85 | (6) | |
86 | mount options: per-mount options (see | |
87 | .BR mount (2)). | |
88 | .TP | |
89 | (7) | |
90 | optional fields: zero or more fields of the form "tag[:value]"; see below. | |
91 | .TP | |
92 | (8) | |
93 | separator: the end of the optional fields is marked by a single hyphen. | |
94 | .TP | |
95 | (9) | |
96 | filesystem type: the filesystem type in the form "type[.subtype]". | |
97 | .TP | |
98 | (10) | |
99 | mount source: filesystem-specific information or "none". | |
100 | .TP | |
101 | (11) | |
102 | super options: per-superblock options (see | |
103 | .BR mount (2)). | |
104 | .RE | |
105 | .IP | |
106 | Currently, the possible optional fields are | |
107 | .IR shared , | |
108 | .IR master , | |
109 | .IR propagate_from , | |
110 | and | |
111 | .IR unbindable . | |
112 | See | |
113 | .BR mount_namespaces (7) | |
114 | for a description of these fields. | |
115 | Parsers should ignore all unrecognized optional fields. | |
116 | .IP | |
117 | For more information on mount propagation see | |
118 | .I Documentation/filesystems/sharedsubtree.rst | |
119 | (or | |
120 | .I Documentation/filesystems/sharedsubtree.txt | |
121 | before Linux 5.8) | |
122 | in the Linux kernel source tree. | |
123 | .SH SEE ALSO | |
124 | .BR proc (5) |