1nss(5) File Formats Manual nss(5)
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6 nss - Name Service Switch configuration file
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10 Each call to a function which retrieves data from a system database
11 like the password or group database is handled by the Name Service
12 Switch implementation in the GNU C library. The various services pro‐
13 vided are implemented by independent modules, each of which naturally
14 varies widely from the other.
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16 The default implementations coming with the GNU C library are by
17 default conservative and do not use unsafe data. This might be very
18 costly in some situations, especially when the databases are large.
19 Some modules allow the system administrator to request taking shortcuts
20 if these are known to be safe. It is then the system administrator's
21 responsibility to ensure the assumption is correct.
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23 There are other modules where the implementation changed over time. If
24 an implementation used to sacrifize speed for memory consumption it
25 might create problems if the preference is switched.
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27 The /etc/default/nss file contains a number of variable assignments.
28 Each variable controls the behavior of one or more NSS modules. White
29 spaces are ignored. Lines beginning with `#' are treated as comments.
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31 The variables currently recognized are:
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33 NETID_AUTHORITATIVE = TRUE|FALSE
34 If set to TRUE, the NIS backend for the initgroups(3) function
35 will accept the information from the netid.byname NIS map as
36 authoritative. This can speed up the function significantly if
37 the group.byname map is large. The content of the netid.byname
38 map is used as is. The system administrator has to make sure it
39 is correctly generated.
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42 SERVICES_AUTHORITATIVE = TRUE|FALSE
43 If set to TRUE, the NIS backend for the getservbyname(3) and
44 getservbyname_r(3) function will assume services.byservicename
45 NIS map exists and is authoritative, particularly that it con‐
46 tains both keys with /proto and without /proto for both primary
47 service names and service aliases. The system administrator has
48 to make sure it is correctly generated.
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51 SETENT_BATCH_READ = TRUE|FALSE
52 If set to TRUE, the NIS backend for the setpwent(3) and set‐
53 grent(3) functions will read the entire database at once and
54 then hand out the requests one by one from memory with every
55 corresponding getpwent(3) or getgrent(3) call respectively.
56 Otherwise each getpwent(3) or getgrent(3) call might result into
57 a network communication with the server to get the next entry.
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62 The default configuration corresponds to the following configuration
63 file:
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65 NETID_AUTHORITATIVE=FALSE
66 SERVICES_AUTHORITATIVE=FALSE
67 SETENT_BATCH_READ=FALSE
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72 /etc/default/nss
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76 Ulrich Drepper <drepper@redhat.com>
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80 nsswitch.conf
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84nss May 2006 nss(5)