group(4) File Formats group(4)NAMEgroup - 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, 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 can not exceed, MAXGLEN-1, which is usually eight
characters.
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 interop‐
erability and compatibility, administrators are recommended to assign
groups using the range of GIDs below 60000 where possible.
A password can be demanded by newgrp(1) if the group password field is
not empty. The only way to create a password for a group is to use
password(1), then cut and paste the password from /etc/shadow to
/etc/group. Group passwords are antiquated and not often used.
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 is given and subsequent group specifications
is ignored.
Malformed entries cause routines that read this file to halt, in which
case group assignments specified further along are never made. To pre‐
vent this from happening, use grpck(1B) to check the /etc/group data‐
base 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 might not be sup‐
ported in future releases. A possible sources is files followed by
ldap. This has the effect of incorporating information from an LDAP
server after the group file.
EXAMPLES
Example 1 An 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 has members larry, moe, and
curly, and all groups listed on the LDAP server are effectively incor‐
porated 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 ALSOgroups(1), grpck(1B), newgrp(1), groupadd(1M), groupdel(1M), group‐
mod(1M), getgrnam(3C), initgroups(3C), nsswitch.conf(4),
unistd.h(3HEAD)
System Administration Guide: Basic Administration
SunOS 5.11 22 Feb 2010 group(4)
