/etc/group: Explanation & Insights

Information about user groups

In Linux and other Unix-like operating systems, the /etc/group file is a text file that stores information about the groups on the system. Each line in the file represents a group, and contains four fields separated by colons:

• The name of the group
• The group password (usually set to an asterisk to indicate that the password is stored elsewhere, such as in the /etc/shadow file)
• The group ID (a unique numerical identifier for the group)
• A list of user names that are members of the group, separated by commas

Here is an example of what a group entry in /etc/group might look like:

developers:*:1001:jane,john,bob

This entry defines a group called "developers" with group ID 1001, and lists three user names (jane, john, and bob) as members of the group.

The /etc/groups file is used by the operating system to determine which users belong to which groups, and is used to assign group permissions to files and directories. It is typically managed by the groupadd, groupmod, and groupdel commands, which are used to add, modify, and delete group entries in the file.