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GROUP (5) | File formats and conventions | Unix Manual Pages | :man


group - format of the group permissions file


See Also


The group file 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 file group consists of newline separated ASCII records, one per group, containing four colon ‘:’ separated fields. These fields are as follows:

group Name of the group.
passwd Group’s encrypted password.
gid The group’s decimal ID.
member Group members.

Lines whose first non-whitespace character is a pound-sign (#) are comments, and are ignored. Blank lines that consist only of spaces, tabs or newlines are also ignored.

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 newlines. 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 group file.


There are various limitations which are explained in the function where they occur; see section SEE ALSO.

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