group(4) File Formats group(4)
NAME
group - group file
DESCRIPTION
The group file is a local source of group information. The group file can be used in conjunction with other group sources, including the
NIS maps group.byname and group.bygid, the NIS+ table group, or group information stored on an LDAP server. Programs use the getgrnam(3C)
routines to access this information.
The group file contains a one-line entry for each group recognized by the system, of the form:
groupname:password: gid:user-list
where
groupname The name of the group. A string consisting of lower case alphabetic characters and numeric characters. Neither a colon (:) nor
a NEWLINE can be part of a groupname. The string must be less than MAXGLEN-1, usually 8, characters long.
gid The group's unique numerical ID (GID) within the system.
user-list A comma-separated list of users allowed in the group.
The maximum value of the gid field is 2147483647. To maximize interoperability and compatibility, administrators are recommended to assign
groups using the range of GIDs below 60000 where possible.
If the password field is empty, no password is demanded. During user identification and authentication, the supplementary group access list
is initialized sequentially from information in this file. If a user is in more groups than the system is configured for, {NGROUPS_MAX}, a
warning will be given and subsequent group specifications will be ignored.
Malformed entries cause routines that read this file to halt, in which case group assignments specified further along are never made. To
prevent this from happening, use grpck(1B) to check the /etc/group database from time to time.
If the number of characters in an entry exceeds 2047, group maintenance commands, such as groupdel(1M) and groupmod(1M), fail.
Previous releases used a group entry beginning with a `+' (plus sign) or `-' (minus sign) to selectively incorporate entries from a naming
service source (for example, an NIS map or data from an LDAP server) for group. If still required, this is supported by specifying
group:compat in nsswitch.conf(4). The compat source may not be supported in future releases. Possible sources are files followed by ldap or
nisplus. This has the effect of incorporating information from an LDAP server or the entire contents of the NIS+ group table after the
group file.
EXAMPLES
Example 1 Example group File.
The following is an example of a group file:
root::0:root
stooges:q.mJzTnu8icF.:10:larry,moe,curly
and the sample group entry from nsswitch.conf:
group: files ldap
With these entries, the group stooges will have members larry, moe, and curly, and all groups listed on the LDAP server are effectively
incorporated after the entry for stooges.
If the group file was:
root::0:root
stooges:q.mJzTnu8icF.:10:larry,moe,curly
+:
and the group entry from nsswitch.conf:
group: compat
all the groups listed in the NIS group.bygid and group.byname maps would be effectively incorporated after the entry for stooges.
SEE ALSO
groups(1), grpck(1B), newgrp(1), groupadd(1M), groupdel(1M), groupmod(1M), getgrnam(3C), initgroups(3C), nsswitch.conf(4), unistd.h(3HEAD)
System Administration Guide: Basic Administration
SunOS 5.11 27 Aug 2008 group(4)