subuid(5) — Linux manual page


SUBUID(5)               File Formats and Conversions               SUBUID(5)

NAME         top

       subuid - the subordinate uid file

DESCRIPTION         top

       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         top

           Per user subordinate user IDs.

           Backup file for /etc/subuid.

SEE ALSO         top

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

COLOPHON         top

       This page is part of the shadow-utils (utilities for managing
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shadow-utils 4.8.1               08/13/2020                        SUBUID(5)

Pages that refer to this page: newuidmap(1)subgid(5)user_namespaces(7)newusers(8)useradd(8)userdel(8)usermod(8)