SUBGID(5)               File Formats and Conversions               SUBGID(5)

NAME         top

       subgid - the subordinate gid file

DESCRIPTION         top

       Each line in /etc/subgid contains a user name and a range of
       subordinate group 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 group ID

       ·   numerical subordinate group ID count

       This file specifies the group IDs that ordinary users can use, with
       the newgidmap command, to configure gid 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/subgid, 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 group IDs.

           Backup file for /etc/subgid.

SEE ALSO         top

       login.defs(5), newgidmap(1), newuidmap(1), newusers(8), subuid(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 ⟨⟩.  If
       you have a bug report for this manual page, see 
       ⟨⟩.  This page was
       obtained from the project's upstream Git repository 
       ⟨git://⟩ on 2017-03-13.
       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

shadow-utils 4.4                 02/18/2017                        SUBGID(5)