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
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
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 parameters. 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.
/etc/group - group account information
/etc/gshadow - encrypted passwords and group administrator
/etc/passwd - user information
groupmod(8), group(5), passwd(5),
The grpck command exits with the following
One or more bad group entries
Cannot open group files
Cannot lock group files
Cannot update group files
Julianne Frances Haugh (email@example.com)