1SUBUID(5)                File Formats and Conversions                SUBUID(5)
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NAME

6       subuid - the subordinate uid file
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DESCRIPTION

9       Each line in /etc/subuid contains a user name and a range of
10       subordinate user ids that user is allowed to use. This is specified
11       with three fields delimited by colons (“:”). These fields are:
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13       ·   login name or UID
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15       ·   numerical subordinate user ID
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17       ·   numerical subordinate user ID count
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19       This file specifies the user IDs that ordinary users can use, with the
20       newuidmap command, to configure uid mapping in a user namespace.
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22       Multiple ranges may be specified per user.
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24       When large number of entries (10000-100000 or more) are defined in
25       /etc/subuid, parsing performance penalty will become noticeable. In
26       this case it is recommended to use UIDs instead of login names.
27       Benchmarks have shown speed-ups up to 20x.
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FILES

30       /etc/subuid
31           Per user subordinate user IDs.
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33       /etc/subuid-
34           Backup file for /etc/subuid.
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SEE ALSO

37       login.defs(5), newgidmap(1), newuidmap(1), newusers(1), subgid(5),
38       useradd(8), userdel(8), usermod(8), user_namespaces(7).
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42shadow-utils 4.6                  02/02/2019                         SUBUID(5)
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