grpck Command

Purpose

Verifies the correctness of a group definition. This document describes both the AIX® grpck command and the System V grpck command.

Syntax

grpck { -n | -p | -t | -y } { ALL | Group ... }

Description

The grpck command verifies the correctness of the group definitions in the user database files by checking the definitions for all the groups or for the groups that are specified by the Group parameter. If more than one group is specified, there must be a space between the groups.

Note: This command writes its messages to stderr.

You must select a flag to indicate whether the system must try to fix erroneous attributes. The following attributes are checked:

Item	Description
name	Checks the uniqueness and composition of the group name. The group name must be a unique string of 8 bytes or less. It cannot begin with a + (plus sign), a : (colon), a - (minus sign), or a ~ (tilde). It cannot contain a : (colon) in the string and cannot be the `ALL` or `default` keywords. No system fix is possible.
groupID	Checks the uniqueness and composition of the group ID. The ID must not be null and must consist of decimal digits only. No system fix is possible.
users	Checks the existence of the users that are listed in the group database files. If you indicate that the system must fix errors, it deletes all the users that are not found in the user database files.
adms	Checks the existence of the users that are listed as group administrators in the group database files. If you indicate that the system must fix errors, it deletes all the administrators that are not found in the user database files.
admin	Checks for a valid admin attribute for each group in the /etc/security/group file. No system fix is available.

Generally, the sysck command calls the grpck command as part of the verification of a trusted-system installation. In addition, the root user or a member of the security group can enter the command.

The grpck command checks to see whether the database management security files (/etc/passwd.nm.idx, /etc/passwd.id.idx, /etc/security/passwd.idx, and /etc/security/lastlog.idx) files are up-to-date or newer than the corresponding system security files. It is acceptable for /etc/security/lastlog.idx to be not newer than /etc/security/lastlog. If the database management security files are out-of-date, a warning message appears indicating that the root user must run the mkpasswd command.

Flags

Item	Description
-n	Reports errors but does not fix them.
-p	Fixes errors but does not report them.
-t	Reports errors and asks if they must be fixed.
-y	Fixes errors and reports them.

Security

Access Control: This command must grant execute (x) access to the root user and members of the security group. The setuid command for the root user must have the trusted computing base attribute.

Files Accessed:

Mode	File
r	/etc/passwd
r	/etc/security/user
rw	/etc/security/group
rw	/etc/group

Auditing Events:

Event	Information
GROUP_User	user, groups, attribute \| error, status
GROUP_Adms	user, groups, attribute \| error, status

Attention RBAC users and Trusted AIX users: This command can perform privileged operations. Only privileged users can run privileged operations. For more information about authorizations and privileges, see Privileged Command Database in Security. For a list of privileges and the authorizations associated with this command, see the lssecattr command or the getcmdattr subcommand.

Examples

To verify that all the group members and administrators exist in the user database, and to report all the errors but not fix them, enter the following command:
```
grpck  -n ALL
```
To verify that all the group members and administrators exist in the user database, and to fix all the errors but not report them, enter the following command:
```
grpck  -p ALL
```
To verify the uniqueness of the group name and group ID defined for the install group, enter the following command:
```
grpck  -n install
```
Or,
```
grpck  -t install
```
Or,
```
grpck  -y install
```
The grpck command does not correct the group names and IDs. Therefore, the -n, -t, and -y flags report problems with group names and group IDs, but do not correct them.

Files

Item	Description
/usr/sbin/grpck	Contains the grpck command.
/etc/passwd	Contains the basic attributes of users.
/etc/security/user	Contains the extended attributes of users.
/etc/group	Contains the basic attributes of groups.
/etc/security/group	Contains the extended attributes of groups.

System V grpck command

Syntax

/usr/sysv/bin/grpck

Description

The /usr/sysv/bin/grpck command verifies the correctness of the group definitions in the user database files by checking the definitions for all the groups. This /usr/sysv/bin/grpck command is a System V version of the existing grpck command in /usr/sbin/. This command calls the /usr/sbin/grpck command with the -n flag and ALL options.

Exit Status

0: Successful completion.
>0: An error occurred.

Examples

To verify that all the group members and administrators exist in the user database, and have any errors that are reported (but not fixed), enter the following command:
```
/usr/sysv/bin/grpck
```

Files

/usr/sysv/bin/grpck: Contains the System V version of the grpck command.