Linux Groups and the /etc/group File Flashcards
A group is just an …?
integer group id (gid).
Every process that runs on the system runs under a…?
collection of groups (gids)
The /etc/group file maps gids to…?
group names and group memberships.
Every file in the filesystem is owned by…?
a single gid.
Users have a single primary group defined in…?
the /etc/passwd file
Users may be members of multiple …?
secondary groups, defined in the /etc/groups file.
Group memberships allow system administrators to…?
efficiently manage collections of users with similar objectives.
Every user is a member of…?
one primary group.
Users can be a member of zero or more…?
secondary groups.
To the Linux kernel, a group is referenced using a…?
32 bit integer group id (GID).
The /etc/group file associates group names with..?
GIDs (for humans), and defines which users belong to which groups.
The /etc/group file plays a similar role for groups as the…?
/etc/passwd file plays for users, has a similar structure, and more reasonable name. It is a line based configuration file, with each consisting of colon separated fields.
/etc/group file fields:
Field 1…?
Group names, the group name is used to give a human readable name to the group.
/etc/group file fields:
Field 2…?
Group Password, Groups can be supplied with a group password, though this is rarely done.
/etc/group file fields:
Field 3…?
Group ID (GID), The integer group id.
/etc/group file fields:
Field 4…?
Group members, A comma separated list of usernames defining the group members.
Group memberships are most often used to determine who has…?
access to what in the filesystem.
Every file on the system is owned by…?
is owned by a user and also owned by a group, which is referred to as the “group owner” of the file.
Because every file must have a group owner, there must be a …?
default group associated with each user. This default group becomes the group owner of newly created files. This group is known as a user’s primary group.
A user’s primary group is defined in the…?
fourth field of a user’s /etc/passwd entry.
In addition to a primary group, users may optionally belong to…?
other groups as well. These groups are termed secondary groups, and are defined (coincidentally) in the fourth field of the /etc/group file.
A user’s secondary groups are defined by…?
adding the username to the fourth field of the appropriate lines in the /etc/group file.
Standard users do not have….?
permission to edit the /etc/passwd file or the /etc/group file, and therefore cannot change their group memberships. Instead, only the administrative user, root, may change group memberships.
If you access to a machine as root, group memberships may be modified using the…?
usermod and groupmod command line utilities, or the system-config-users graphical utility.
