Group (database)

Group is a name service database used to store group information on Unix-like operating systems. The sources for the group database (and hence the sources for groups on a system) are configured, like other name service databases, in nsswitch.conf. The database file is located at /etc/group. It contains fields representing the group name, group id, encrypted password, and users belonging to the group. These fields are stored in a structure defined in the header file <grp.h>.[1]

Seeing available groups on a Unix system

The contents of the group database (and available groups) can be seen with a variety of tools:

C

The <grp.h> header file contains the functions getgrgid and getgrname to look up a group by its ID or Name, as well as the functions setgrent, getgrent, and endgrent to iterate through all groups.[1]

Command line

The getent command can be used to fetch group information.

Fetching a list of all available groups

getent group

Fetching a specific group

For a specific group called 'users':

getent group users

Python

grp - The Group Database — a Python module

References

Stevens, W. Richard; Rago, Stephen A. (2013). Advanced programming in the UNIX environment (third ed.). Upper Saddle River (NJ): Addison-Wesley. pp. 182–183. ISBN 978-0-321-63773-4.

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[Unix-1] Stevens, W. Richard; Rago, Stephen A. (2013). Advanced programming in the UNIX environment (third ed.). Upper Saddle River (NJ): Addison-Wesley. pp. 182–183. ISBN 978-0-321-63773-4.