grpck
verify integrity of group files
see also :
groupmod - passwd - pwck
Synopsis
grpck [options]
[group [ shadow ]]
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description
The
grpck command verifies the integrity of the groups
information. It checks that all entries in /etc/group and
/etc/gshadow have the proper format and contain valid data.
The user is prompted to delete entries that are improperly
formatted or which have other uncorrectable errors.
Checks are made
to verify that each entry has:
• the
correct number of fields
• a unique
and valid group name
• a valid
group identifier (/etc/group only)
• a valid
list of members and administrators
• a
corresponding entry in the /etc/gshadow file (respectively
/etc/group for the gshadow checks)
The checks for
correct number of fields and unique group name are fatal. If
an entry has the wrong number of fields, the user will be
prompted to delete the entire line. If the user does not
answer affirmatively, all further checks are bypassed. An
entry with a duplicated group name is prompted for deletion,
but the remaining checks will still be made. All other
errors are warnings and the user is encouraged to run the
groupmod command to correct the error.
The commands
which operate on the /etc/group and /etc/gshadow files are
not able to alter corrupted or duplicated entries.
grpck should be used in those circumstances to remove
the offending entries.
options
The
-r and -s options cannot be
combined.
The options
which apply to the grpck command are:
-h,
--help
Display help message and
exit.
-r,
--read-only
Execute the grpck
command in read-only mode. This causes all questions
regarding changes to be answered no without user
intervention.
-R,
--root CHROOT_DIR
Apply changes in the
CHROOT_DIR directory and use the configuration files
from the CHROOT_DIR directory.
-s,
--sort
Sort entries in /etc/group and
/etc/gshadow by GID.
By default,
grpck operates on /etc/group and /etc/gshadow. The
user may select alternate files with the group and
shadow parameters.
configuration
The following configuration variables in /etc/login.defs change
the behavior of this tool:
MAX_MEMBERS_PER_GROUP (number)
Maximum members per group entry. When the maximum is reached, a
new group entry (line) is started in /etc/group (with the same
name, same password, and same GID).
The default value is 0, meaning that there are no limits in the
number of members in a group.
This feature (split group) permits to limit the length of lines
in the group file. This is useful to make sure that lines for NIS
groups are not larger than 1024 characters.
If you need to enforce such limit, you can use 25.
Note: split groups may not be supported by all tools (even in the
Shadow toolsuite). You should not use this variable unless you
really need it.
exit values
The grpck command exits with the following values:
0
success
1
invalid command syntax
2
one or more bad group entries
3
can't open group files
4
can't lock group files
5
can't update group files
files
/etc/group
Group account information.
/etc/gshadow
Secure group account information.
/etc/passwd
User account information.
see also
group,
groupmod , gshadow, passwd ,
pwck , shadow.