Provided by: passwd_4.5-1ubuntu2.5_amd64 bug


       subuid - the subordinate uid file


       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:

       •   login name or UID

       •   numerical subordinate user ID

       •   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.

       When large number of entries (10000-100000 or more) are defined in /etc/subuid, 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 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).