Group contains for each group the following information:
This is an ASCII file. The fields are separated by colons; each group is separated from the next by a new-line. If the password field is null, no password is demanded.
This file resides in the /etc directory. Because of the encrypted passwords, it can and does have general read permission and can be used, for example, to map numerical group ID's to names.
A group file can have a line beginning with a plus (+), which means to incorporate entries from the yellow pages. There are two styles of + entries: All by itself, + means to insert the entire contents of the yellow pages group file at that point; +name means to insert the entry (if any) for name from the yellow pages at that point. If a + entry has a non-null password or group member field, the contents of that field will overide what is contained in the yellow pages. 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 - entries: An entry that consists of -name means to disallow any subsequent entry (if any) for name. These entries will be disallowed regardless of whether the subsequent entry comes from the yellow pages or the local group file.
-oldproj +myproject:::bill, steve +:
If these entries appear at the end of a group file, then the group
oldproj
will be ignored if it appears after the entry
-oldproj.
Also, the group
myproject
will have members
billandsteve,
and the password and group ID of the yellow pages entry for the group
myproject.
All the groups listed in the yellow pages
will be pulled in and placed after the entry for
myproject.