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

       /etc/subuid
           Per user subordinate user IDs.

       /etc/subuid-
           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
       accounts and shadow password files) project.  Information about the
       project can be found at ⟨https://github.com/shadow-maint/shadow⟩.  If
       you have a bug report for this manual page, send it to
       pkg-shadow-devel@alioth-lists.debian.net.  This page was obtained
       from the project's upstream Git repository
       ⟨https://github.com/shadow-maint/shadow⟩ on 2019-11-19.  (At that
       time, the date of the most recent commit that was found in the repos‐
       itory was 2019-11-16.)  If you discover any rendering problems in
       this HTML version of the page, or you believe there is a better or
       more up-to-date source for the page, or you have corrections or
       improvements to the information in this COLOPHON (which is not part
       of the original manual page), send a mail to man-pages@man7.org

shadow-utils 4.6                 11/19/2019                        SUBUID(5)

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

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