SUBGID(5)                 File Formats and Conversions                 SUBGID(5)

       subgid - the subordinate gid file

       Each line in /etc/subgid contains a user name and a range of subordinate
       group ids that user is allowed to use. This is specified with three
       fields delimited by colons (“:”). These fields are:

       •   login name or UID

       •   numerical subordinate group ID

       •   numerical subordinate group ID count

       This file specifies the group IDs that ordinary users can use, with the
       newgidmap command, to configure gid mapping in a user namespace.

       Multiple ranges may be specified per user.

       When large number of entries (10000-100000 or more) are defined in
       /etc/subgid, parsing performance penalty will become noticeable. In this
       case it is recommended to use UIDs instead of login names. Benchmarks
       have shown speed-ups up to 20x.

           Per user subordinate group IDs.

           Backup file for /etc/subgid.

       login.defs(5), newgidmap(1), newuidmap(1), newusers(8), subuid(5),
       useradd(8), userdel(8), usermod(8), user_namespaces(7).

shadow-utils 4.8.1                 01/23/2020                          SUBGID(5)