# SUBGID - the configuration for subordinate group ids - man(5) - [phpMan]

[_SUBGID_(5)](https://www.chedong.com/phpMan.php/man/SUBGID/5/markdown)                          File Formats and Configuration                          [_SUBGID_(5)](https://www.chedong.com/phpMan.php/man/SUBGID/5/markdown)

## NAME
       subgid - the configuration for subordinate group ids

## DESCRIPTION
       Subgid authorizes a group id to map ranges of group ids from its namespace into child
       namespaces.

       The delegation of the subordinate gids can be configured via the _subid_ field in
       /etc/nsswitch.conf file. Only one value can be set as the delegation source. Setting this
       field to _files_ configures the delegation of gids to /etc/subgid. Setting any other value
       treats the delegation as a plugin following with a name of the form _libsubid_$value.so_. If
       the value or plugin is missing, then the subordinate gid delegation falls back to _files_.

       Note, that **groupadd **will only create entries in /etc/subgid if subid delegation is managed
       via subid files.

## LOCAL SUBORDINATE DELEGATION
       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
       /etc/subgid
           Per user subordinate group IDs.

       /etc/subgid-
           Backup file for /etc/subgid.

## SEE ALSO
       [**login.defs**(5)](https://www.chedong.com/phpMan.php/man/login.defs/5/markdown), [**newgidmap**(1)](https://www.chedong.com/phpMan.php/man/newgidmap/1/markdown), [**newuidmap**(1)](https://www.chedong.com/phpMan.php/man/newuidmap/1/markdown), [**newusers**(8)](https://www.chedong.com/phpMan.php/man/newusers/8/markdown), [**subuid**(5)](https://www.chedong.com/phpMan.php/man/subuid/5/markdown), [**useradd**(8)](https://www.chedong.com/phpMan.php/man/useradd/8/markdown), [**userdel**(8)](https://www.chedong.com/phpMan.php/man/userdel/8/markdown),
       [**usermod**(8)](https://www.chedong.com/phpMan.php/man/usermod/8/markdown), [**user_namespaces**(7)](https://www.chedong.com/phpMan.php/man/usernamespaces/7/markdown).

shadow-utils 4.13                            05/30/2024                                    [_SUBGID_(5)](https://www.chedong.com/phpMan.php/man/SUBGID/5/markdown)