GRPCK linux command manual
grpck - verify integrity of group files
grpck [-r] [group shadow]
grpck verifies the integrity of the system authentication information.
All entries in the /etc/group and /etc/gshadow are checked to see that
the entry has the proper format and valid data in each field. The
user is prompted to delete entries that are improperly formatted or
which have other incorrectable errors.
Checks are made to verify that each entry has
- the correct number of fields
- a unique group name
- a valid list of members and administrators
The checks for correct number of fields and unique group name are
fatal. If the 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 file are not able to
alter corrupted or duplicated entries. grpck should be used in those
circumstances to remove the offending entry.
By default, grpck operates on the files /etc/group and /etc/gshadow.
The user may select alternate files with the group and shadow parame-
ters. Additionally, the user may execute the command in read-only
mode by specifying the -r flag. This causes all questions regarding
changes to be answered no without user intervention. grpck can also
sort entries in /etc/group and /etc/gshadow by GID. To run it in sort
mode pass it -s flag. No checks are performed then, it just sorts.
/etc/group - group account information
/etc/gshadow - encrypted passwords and group administrator information
/etc/passwd - user information
group(5), passwd(5), shadow(5), groupmod(8)
The grpck command exits with the following values:
1 Syntax Error
2 One or more bad group entries
3 Cannot open group files
4 Cannot lock group files
5 Cannot update group files
Julianne Frances Haugh (firstname.lastname@example.org)