1GRPCK(8) System Management Commands GRPCK(8)
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6 grpck - verify integrity of group files
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9 grpck [options] [group [ shadow ]]
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12 The grpck command verifies the integrity of the groups information. It
13 checks that all entries in /etc/group and /etc/gshadow have the proper
14 format and contain valid data. The user is prompted to delete entries
15 that are improperly formatted or which have other uncorrectable errors.
16 Checks are made to verify that each entry has:
18 • the correct number of fields
20 • a unique and valid group name
22 • a valid group identifier (/etc/group only)
24 • a valid list of members and administrators
26 • a corresponding entry in the /etc/gshadow file (respectively
28 /etc/group for the gshadow checks)
29 The checks for correct number of fields and unique group name are
31 fatal. If an entry has the wrong number of fields, the user will be
32 prompted to delete the entire line. If the user does not answer
33 affirmatively, all further checks are bypassed. An entry with a
34 duplicated group name is prompted for deletion, but the remaining
35 checks will still be made. All other errors are warnings and the user
36 is encouraged to run the groupmod command to correct the error.
37 The commands which operate on the /etc/group and /etc/gshadow files are
39 not able to alter corrupted or duplicated entries. grpck should be
40 used in those circumstances to remove the offending entries.
41
43 The -r and -s options cannot be combined.
44 The options which apply to the grpck command are:
46 -h, --help
48 Display help message and exit.
49 -r, --read-only
51 Execute the grpck command in read-only mode. This causes all
52 questions regarding changes to be answered no without user
53 intervention.
54 -R, --root CHROOT_DIR
56 Apply changes in the CHROOT_DIR directory and use the configuration
57 files from the CHROOT_DIR directory. Only absolute paths are
58 supported.
59 -s, --sort
61 Sort entries in /etc/group and /etc/gshadow by GID.
62 -S, --silence-warnings
64 Suppress more controversial warnings, in particular warnings about
65 inconsistency between group members listed in /etc/group and
66 /etc/ghadow.
67 By default, grpck operates on /etc/group and /etc/gshadow. The user may
69 select alternate files with the group and shadow parameters.
70
72 The following configuration variables in /etc/login.defs change the
73 behavior of this tool:
74 MAX_MEMBERS_PER_GROUP (number)
76 Maximum members per group entry. When the maximum is reached, a new
77 group entry (line) is started in /etc/group (with the same name,
78 same password, and same GID).
79 The default value is 0, meaning that there are no limits in the
81 number of members in a group.
82 This feature (split group) permits to limit the length of lines in
84 the group file. This is useful to make sure that lines for NIS
85 groups are not larger than 1024 characters.
86 If you need to enforce such limit, you can use 25.
88 Note: split groups may not be supported by all tools (even in the
90 Shadow toolsuite). You should not use this variable unless you
91 really need it.
92
94 /etc/group
95 Group account information.
96 /etc/gshadow
98 Secure group account information.
99 /etc/passwd
101 User account information.
102
104 The grpck command exits with the following values:
105 0
107 success
108 1
110 invalid command syntax
111 2
113 one or more bad group entries
114 3
116 can't open group files
117 4
119 can't lock group files
120 5
122 can't update group files
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125 group(5), groupmod(8), gshadow(5), passwd(5), pwck(8), shadow(5).
126shadow-utils 4.13 03/06/2023 GRPCK(8)