1NSS(5) Linux Programmer's Manual NSS(5)
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6 nss - Name Service Switch configuration file
7
9 Each call to a function which retrieves data from a system database
10 like the password or group database is handled by the Name Service
11 Switch implementation in the GNU C library. The various services pro‐
12 vided are implemented by independent modules, each of which naturally
13 varies widely from the other.
14 The default implementations coming with the GNU C library are by de‐
16 fault conservative and do not use unsafe data. This might be very
17 costly in some situations, especially when the databases are large.
18 Some modules allow the system administrator to request taking shortcuts
19 if these are known to be safe. It is then the system administrator's
20 responsibility to ensure the assumption is correct.
21 There are other modules where the implementation changed over time. If
23 an implementation used to sacrifice speed for memory consumption, it
24 might create problems if the preference is switched.
25 The /etc/default/nss file contains a number of variable assignments.
27 Each variable controls the behavior of one or more NSS modules. White
28 spaces are ignored. Lines beginning with '#' are treated as comments.
29 The variables currently recognized are:
31 NETID_AUTHORITATIVE = TRUE|FALSE
33 If set to TRUE, the NIS backend for the initgroups(3) function
34 will accept the information from the netid.byname NIS map as au‐
35 thoritative. This can speed up the function significantly if
36 the group.byname map is large. The content of the netid.byname
37 map is used as is. The system administrator has to make sure it
38 is correctly generated.
39 SERVICES_AUTHORITATIVE = TRUE|FALSE
41 If set to TRUE, the NIS backend for the getservbyname(3) and
42 getservbyname_r(3) functions will assume that the services.by‐
43 servicename NIS map exists and is authoritative, particularly
44 that it contains both keys with /proto and without /proto for
45 both primary service names and service aliases. The system ad‐
46 ministrator has to make sure it is correctly generated.
47 SETENT_BATCH_READ = TRUE|FALSE
49 If set to TRUE, the NIS backend for the setpwent(3) and set‐
50 grent(3) functions will read the entire database at once and
51 then hand out the requests one by one from memory with every
52 corresponding getpwent(3) or getgrent(3) call respectively.
53 Otherwise, each getpwent(3) or getgrent(3) call might result in
54 a network communication with the server to get the next entry.
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57 /etc/default/nss
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60 The default configuration corresponds to the following configuration
61 file:
62 NETID_AUTHORITATIVE=FALSE
64 SERVICES_AUTHORITATIVE=FALSE
65 SETENT_BATCH_READ=FALSE
66
68 nsswitch.conf
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71 This page is part of release 5.12 of the Linux man-pages project. A
72 description of the project, information about reporting bugs, and the
73 latest version of this page, can be found at
74 https://www.kernel.org/doc/man-pages/.
75Linux 2020-06-09 NSS(5)