grpck manpage

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GRPCK(8)		  System Management Commands		      GRPCK(8)

       grpck - verify integrity of group files

       grpck [-r] [group [ shadow ]]

       grpck [-s] [group [ shadow ]]

       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:

       o   the correct number of fields

       o   a unique and valid group name

       o   a valid group identifier (/etc/group only)

       o   a valid list of members and administrators

       o   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.

       The options which apply to the grpck command are:

	   Execute the grpck command in read-only mode. This causes all
	   questions regarding changes to be answered no without user

	   Sort entries in /etc/group and /etc/gshadow by GID.

       By default, grpck operates on /etc/groupand /etc/gshadow. The user may
       select alternate files with the group and shadow parameters.

       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.

	   Group account information.

	   Secure group account information.

	   User account information.

       The grpck command exits with the following values:


	   invalid command syntax

	   one or more bad group entries

	   can't open group files

	   can't lock group files

	   can't update group files

       group(5), groupmod(8), gshadow(5), passwd(5), pwck(8), shadow(5).

System Management Commands	  07/24/2009			      GRPCK(8)