The grpck command verifies the integrity of the groups information.
It checks that all entries in /etc/groupand /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
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/groupand /etc/gshadow files
are not able to alter corrupted or duplicated entries. grpck should
be used in those circumstances to remove the offending entries.
The -r and -s options cannot be combined.
The options which apply to the grpck command are:
Display help message and exit.
Execute the grpck command in read-only mode. This causes all
questions regarding changes to be answered no without user
-R, --root CHROOT_DIR
Apply changes in the CHROOT_DIR directory and use the
configuration files from the CHROOT_DIR directory.
Sort entries in /etc/groupand /etc/gshadow by GID.
By default, grpck operates on /etc/groupand /etc/gshadow. The user
may select alternate files with the groupand shadow parameters.
The following configuration variables in /etc/login.defs change the
behavior of this tool:
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.
This page is part of the shadow-utils (utilities for managing
accounts and shadow password files) project. Information about the
project can be found at ⟨http://pkg-shadow.alioth.debian.org/⟩. If
you have a bug report for this manual page, see
⟨http://pkg-shadow.alioth.debian.org/getinvolved.php⟩. This page was
obtained from the project's upstream Git repository
⟨git://anonscm.debian.org/git/pkg-shadow/shadow.git⟩ on 2017-03-13.
If you discover any rendering problems in this HTML version of the
page, or you believe there is a better or more up-to-date source for
the page, or you have corrections or improvements to the information
in this COLOPHON (which is not part of the original manual page),
send a mail to firstname.lastname@example.org
shadow-utils 4.4 02/18/2017 GRPCK(8)