/share/man/man5/group.5

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 32.\"     From: @(#)group.5	8.3 (Berkeley) 4/19/94
 33.\" $FreeBSD$
 34.\"
 35.Dd September 29, 1994
 36.Dt GROUP 5
 37.Os
 38.Sh NAME
 39.Nm group
 40.Nd format of the group permissions file
 41.Sh DESCRIPTION
 42The
 43.Nm
 44file is the local source of group information.
 45It can be used in conjunction with the Hesiod domain
 46`group', and the NIS maps `group.byname' and `group.bygid',
 47as controlled by
 48.Xr nsswitch.conf 5 .
 49.Pp
 50The file
 51.Nm
 52consists of newline separated
 53.Tn ASCII
 54records, one per group, containing four colon
 55.Ql \&:
 56separated fields.
 57These fields are as follows:
 58.Bl -tag -width password -offset indent -compact
 59.It group
 60Name of the group.
 61.It passwd
 62Group's
 63.Em encrypted
 64password.
 65.It gid
 66The group's decimal ID.
 67.It member
 68Group members.
 69.El
 70.Pp
 71Lines whose first non-whitespace character is a pound-sign (#)
 72are comments, and are ignored.
 73Blank lines that consist
 74only of spaces, tabs or newlines are also ignored.
 75.Pp
 76The
 77.Ar group
 78field is the group name used for granting file access to users
 79who are members of the group.
 80The
 81.Ar gid
 82field is the number associated with the group name.
 83They should both be unique across the system (and often
 84across a group of systems) since they control file access.
 85The
 86.Ar passwd
 87field
 88is an optional
 89.Em encrypted
 90password.
 91This field is rarely used
 92and an asterisk is normally placed in it rather than leaving it blank.
 93The
 94.Ar member
 95field contains the names of users granted the privileges of
 96.Ar group .
 97The member names are separated by commas without spaces or newlines.
 98A user is automatically in a group if that group was specified
 99in their
100.Pa /etc/passwd
101entry and does not need to be added to that group in the
102.Nm
103file.
104.\" .Pp
105.\" When the system reads the file
106.\" .Pa /etc/group
107.\" the fields are read into the structure
108.\" .Fa group
109.\" declared in
110.\" .In grp.h :
111.\" .Bd -literal -offset indent
112.\" struct group {
113.\"	char    *gr_name;        /* group name */
114.\"	char    *gr_passwd;      /* group password */
115.\"	int     gr_gid;          /* group id */
116.\"	char    **gr_mem;        /* group members */
117.\" };
118.\" .Ed
119.Sh LIMITS
120There are various limitations which are explained in
121the function where they occur; see section
122.Sx SEE ALSO .
123.Pp
124In older implementations,
125a group cannot have more than 200 members.
126The maximum line length of
127.Pa /etc/group
128is 1024 characters.
129Longer lines will be skipped.
130This limitation disappeared in
131.Fx 3.0 .
132Older binaries that are statically linked, depend on old
133shared libraries, or
134.No non- Ns Fx
135binaries in compatibility mode
136may still have this limit.
137.Sh FILES
138.Bl -tag -width /etc/group -compact
139.It Pa /etc/group
140.El
141.Sh SEE ALSO
142.Xr passwd 1 ,
143.Xr setgroups 2 ,
144.Xr crypt 3 ,
145.Xr getgrent 3 ,
146.Xr initgroups 3 ,
147.Xr nsswitch.conf 5 ,
148.Xr passwd 5 ,
149.Xr chkgrp 8 ,
150.Xr pw 8 ,
151.Xr yp 8
152.Sh HISTORY
153A
154.Nm
155file format appeared in
156.At v6 .
157Support for comments first appeared in
158.Fx 3.0 .
159.Sh BUGS
160The
161.Xr passwd 1
162command does not change the
163.Nm
164passwords.