NAME

group, logingroup − group file, grp.h

DESCRIPTION

group contains for each group the following information:

• group name

• encrypted password

• numerical group ID

• comma-separated list of all users allowed in the group

This is an ASCII file.  Fields are separated by colons, and each group is separated from the next by a new-line.  No spaces should separate the fields or parts of fields on any line.  If the password field is null, no password is associated with the group. 

There are two files of this form in the system, /etc/group and /etc/logingroup.  The file /etc/group exists to supply names for each group, and to support changing groups via newgrp(1). /etc/logingroup provides a default group access list for each user via login(1) and initgroups(3C).

The real and effective group ID set up by login for each user is defined in /etc/passwd (see passwd(4)). If /etc/logingroup is empty or non-existent, the default group access list is empty.  If /etc/logingroup and /etc/group are links to the same file, the default access list includes the entire set of groups associated with the user.  The group name and password fields in /etc/logingroup are never used; they are included only to give the two files a uniform format, allowing them to be linked together. 

All group IDs used in /etc/logingroup or /etc/passwd should be defined in /etc/group.  No user should be associated with more than NGROUPS (see setgroups(2)) groups in /etc/logingroup. 

These files reside in directory /etc.  Because of the encrypted passwords, these files can and do have general read permission and can be used, for example, to map numerical group IDs to names. 

The group structure is defined in <grp.h> and includes the following members:

NETWORKING FEATURES

NFS

The /etc/group file can have a line beginning with a plus (+), which means to incorporate entries from the Network Information Service (NIS).  There are two styles of + entries: + means to insert the entire contents of the NIS group file at that point, and +name means to insert the entry (if any) for name from the NIS at that point.  If a + entry has a non-null password or group member field, the contents of that field overide what is contained in the NIS.  The numerical group ID field cannot be overridden. 

A group file can also have a line beginning with a minus (−), these entries are used to disallow group entries.  There is only one style of − entry; an entry that consists of −name means to disallow any subsequent entry (if any) for name. These entries are disallowed regardless of whether the subsequent entry comes from the NIS or the local group file. 

WARNINGS

Group ID (gid) 9 is reserved for the Pascal Language operating system and the BASIC Language operating system.  These are operating systems for Series 300/400 computers that can co-exist with HP-UX on the same disk.  Using this gid for other purposes can inhibit file transfer and sharing. 

If /etc/group is linked to /etc/logingroup, group membership for a user is managed by NIS, and no NIS server is able to respond, that user cannot log in until a server does respond. 

DEPENDENCIES

NFS

EXAMPLES

Here is a sample /etc/group file:

Group other has a gid of 1 and members root, daemon, uucp, who, date, and sync. The group oldproj is ignored since it appears after the entry -oldproj. Also, the group myproject has members bill and steve, and the password and group ID of the NIS entry for the group myproject. All groups listed in the NIS are pulled in and placed after the entry for myproject.

WARNINGS
The plus (+) and minus (−) features are part of NFS.  Therefore if NFS is not installed, these features cannot work. 

FILES

/etc/group
/etc/logingroup

SEE ALSO

groups(1), newgrp(1), passwd(1), setgroups(2), crypt(3C), getgrent(3C), initgroups(3C), passwd(4). 

WARNINGS

There is no single tool available to completely ensure that /etc/passwd, /etc/group, and /etc/logingroup are compatible.  However, pwck(1M) and grpck(1M) can be used to simplify the task.

There is no tool for setting group passwords in /etc/group. 

STANDARDS CONFORMANCE

group: SVID2, XPG2

Hewlett-Packard Company  —  HP-UX Release 8.05: June 1991