| .\" Copyright (C) 2006 Red Hat, Inc. All rights reserved. |
| .\" Author: Ulrich Drepper <drepper@redhat.com> |
| .\" |
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| .\" This copyrighted material is made available to anyone wishing to use, |
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| .\" GNU General Public License v.2. |
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| .\" ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| .\" FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for |
| .\" more details. |
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| .\" You should have received a copy of the GNU General Public |
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| .\" |
| .TH NSS 5 2020-06-09 "Linux" "Linux Programmer's Manual" |
| .SH NAME |
| nss \- Name Service Switch configuration file |
| .SH DESCRIPTION |
| Each call to a function which retrieves data from a system database |
| like the password or group database is handled by the Name Service |
| Switch implementation in the GNU C library. |
| The various services |
| provided are implemented by independent modules, each of which |
| naturally varies widely from the other. |
| .PP |
| The default implementations coming with the GNU C library are by |
| default conservative and do not use unsafe data. |
| This might be very costly in some situations, especially when the databases |
| are large. |
| Some modules allow the system administrator to request |
| taking shortcuts if these are known to be safe. |
| It is then the system administrator's responsibility to ensure the assumption |
| is correct. |
| .PP |
| There are other modules where the implementation changed over time. |
| If an implementation used to sacrifice speed for memory consumption, |
| it might create problems if the preference is switched. |
| .PP |
| The |
| .I /etc/default/nss |
| file contains a number of variable assignments. |
| Each variable controls the behavior of one or more |
| NSS modules. |
| White spaces are ignored. |
| Lines beginning with \(aq#\(aq |
| are treated as comments. |
| .PP |
| The variables currently recognized are: |
| .TP |
| \fBNETID_AUTHORITATIVE =\fR \fITRUE\fR|\fIFALSE\fR |
| If set to TRUE, the NIS backend for the |
| .BR initgroups (3) |
| function will accept the information |
| from the |
| .I netid.byname |
| NIS map as authoritative. |
| This can speed up the function significantly if the |
| .I group.byname |
| map is large. |
| The content of the |
| .I netid.byname |
| map is used \fBas is\fR. |
| The system administrator has to make sure it is correctly generated. |
| .TP |
| \fBSERVICES_AUTHORITATIVE =\fR \fITRUE\fR|\fIFALSE\fR |
| If set to TRUE, the NIS backend for the |
| .BR getservbyname (3) |
| and |
| .BR getservbyname_r (3) |
| functions will assume that the |
| .I services.byservicename |
| NIS map exists and is authoritative, particularly |
| that it contains both keys with /proto and without /proto for both |
| primary service names and service aliases. |
| The system administrator has to make sure it is correctly generated. |
| .TP |
| \fBSETENT_BATCH_READ =\fR \fITRUE\fR|\fIFALSE\fR |
| If set to TRUE, the NIS backend for the |
| .BR setpwent (3) |
| and |
| .BR setgrent (3) |
| functions will read the entire database at once and then |
| hand out the requests one by one from memory with every corresponding |
| .BR getpwent (3) |
| or |
| .BR getgrent (3) |
| call respectively. |
| Otherwise, each |
| .BR getpwent (3) |
| or |
| .BR getgrent (3) |
| call might result in a network communication with the server to get |
| the next entry. |
| .SH FILES |
| \fI/etc/default/nss\fR |
| .SH EXAMPLES |
| The default configuration corresponds to the following configuration file: |
| .PP |
| .in +4n |
| .EX |
| NETID_AUTHORITATIVE=FALSE |
| SERVICES_AUTHORITATIVE=FALSE |
| SETENT_BATCH_READ=FALSE |
| .EE |
| .in |
| .\" .SH AUTHOR |
| .\" Ulrich Drepper <drepper@redhat.com> |
| .\" |
| .SH SEE ALSO |
| \fInsswitch.conf\fR |