Manpages - subuid.5

subuid - the subordinate uid file

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.

/etc/subuid

Per user subordinate user IDs.

/etc/subuid-

Backup file for /etc/subuid.

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