SUBGID(5)

NAME
subgid - the subordinate gid file

DESCRIPTION

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), newgidmap(1), newuidmap(1), newusers(8), subuid(5), useradd(8), userdel(8), usermod(8), user_namespaces(7).