subgid(5) — Linux manual page


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

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shadow-utils 4.8.1               11/01/2020                        SUBGID(5)

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