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

       o   login name

       o   numerical subordinate user ID

       o   numerical subordinate user ID count

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

       Multiple ranges may be specified per user.

           Per user subordinate user IDs.

           Backup file for /etc/subuid.

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

shadow-utils 4.2                  03/26/2019                         SUBUID(5)
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