NAME

       subuid - the subordinate uid file

DESCRIPTION

       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.

FILES

       /etc/subuid
           Per user subordinate user IDs.

       /etc/subuid-
           Backup file for /etc/subuid.

SEE ALSO

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

shadow-utils 4.5                                   11/29/2022                                          SUBUID(5)