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GROUP(5)		    BSD	File Formats Manual		      GROUP(5)

NAME
     group -- format of	the group permissions file

DESCRIPTION
     The group file /etc/group is the local source of group information.  It
     can be used in conjunction	with the Hesiod	domain `group',	and the	NIS
     maps `group.byname' and `group.bygid', as controlled by nsswitch.conf(5).

     The group file consists of	newline	separated ASCII	records, usually one
     per group,	containing four	colon `:' separated fields.  Each line has the
     form:
	   group:passwd:gid:[member[,member]...]

     These fields are as follows:
	   group     Name of the group.
	   passwd    Group's encrypted password.
	   gid	     The group's decimal ID.
	   member    Group members.

     The group field is	the group name used for	granting file access to	users
     who are members of	the group.

     The gid field is the number associated with the group name.  They should
     both be unique across the system (and often across	a group	of systems)
     since they	control	file access.

     The passwd	field is an optional encrypted password.  This field is	rarely
     used and an asterisk is normally placed in	it rather than leaving it
     blank.

     The member	field contains the names of users granted the privileges of
     group.  The member	names are separated by commas without spaces or	new-
     lines.  A user is automatically in	a group	if that	group was specified in
     their /etc/passwd entry and does not need to be added to that group in
     the /etc/group file.

     Very large	groups can be accommodated over	multiple lines by specifying
     the same group name in all	of them; other than this, each line has	an
     identical format to that described	above.	This can be necessary to avoid
     the record's length limit,	which is currently set to 1024 characters.
     Note that the limit can be	queried	through	sysconf(3) by using the
     _SC_GETGR_R_SIZE_MAX parameter.  For example:

	   biggrp:*:1000:user001,user002,user003,...,user099,user100
	   biggrp:*:1000:user101,user102,user103,...

     The group with the	name "wheel" has a special meaning to the su(1)	com-
     mand: if it exists	and has	any members, only users	listed in that group
     are allowed to su to "root".

HESIOD SUPPORT
     If	`dns' is specified for the `group' database in nsswitch.conf(5), then
     group lookups occur from the `group' Hesiod domain.

NIS SUPPORT
     If	`nis' is specified for the `group' database in nsswitch.conf(5), then
     group lookups occur from the `group.byname' and `group.bygid' NIS map.

COMPAT SUPPORT
     If	`compat' is specified for the `group' database,	and either `dns' or
     `nis' is specified	for the	`group_compat' database	in nsswitch.conf(5),
     then the group file may also contain lines	of the format

     +name:*::

     which causes the specified	group to be included from the `group' Hesiod
     domain or the `group.byname' NIS map (respectively).

     If	no group name is specified, or the plus	sign ("+") appears alone on
     line, all groups are included from	the Hesiod domain or the NIS map.

     Hesiod or NIS compat references may appear	anywhere in the	file, but the
     single plus sign ("+") form should	be on the last line, for historical
     reasons.  Only the	first group with a specific name encountered, whether
     in	the group file itself, or included via Hesiod or NIS, will be used.

FILES
     /etc/group

SEE ALSO
     newgrp(1),	passwd(1), su(1), setgroups(2),	crypt(3), initgroups(3),
     nsswitch.conf(5), passwd(5), yp(8)

HISTORY
     A group file format appeared in Version 6 AT&T UNIX.

     The NIS file format first appeared	in SunOS.

     The Hesiod	support	first appeared in NetBSD 1.4.

BUGS
     The passwd(1) command does	not change the group passwords.

BSD				 June 21, 2007				   BSD

NAME | DESCRIPTION | HESIOD SUPPORT | NIS SUPPORT | COMPAT SUPPORT | FILES | SEE ALSO | HISTORY | BUGS

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