subuid

Description

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

/etc/subuid

Per user subordinate user IDs.

/etc/subuid-

Backup file for /etc/subuid.

See Also

login.defs(5), newgidmap(1), newuidmap(1), newusers(1), subgid(5), useradd(8), userdel(8), usermod(8), user_namespaces(7).

Referenced By

newuidmap(1), newusers(8), podman(1), podman-create(1), podman-run(1), subgid(5), useradd(8), userdel(8), usermod(8), user_namespaces(7).