SUBUID(5) File Formats and Conversions SUBUID(5)
NAME
subuid - the subordinate uid file
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:
o login name or UID
o numerical subordinate user ID
o 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).
shadow-utils 4.5 01/25/2018 SUBUID(5)
