SUBUID(5) File Formats and Conversions 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:
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.
Per user subordinate user IDs.
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).
shadow-utils 4.5 03/22/2019 SUBUID(5)
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