man3/setnetgrent.3

   1 .\"  Copyright 2002 walter harms (walter.harms@informatik.uni-oldenburg.de)
   2 .\"
   3 .\" %%%LICENSE_START(GPL_NOVERSION_ONELINE)
   4 .\" Distributed under GPL
   5 .\" %%%LICENSE_END
   6 .\"
   7 .\"  based on glibc infopages
   8 .\" polished - aeb
   9 .\"
  10 .TH SETNETGRENT 3 2017-09-15 "GNU" "Linux Programmer's Manual"
  11 .SH NAME
  12 setnetgrent, endnetgrent, getnetgrent, getnetgrent_r, innetgr \-
  13 handle network group entries
  14 .SH SYNOPSIS
  15 .nf
  16 .B #include <netdb.h>
  17 .PP
  18 .BI "int setnetgrent(const char *" netgroup );
  19 .PP
  20 .B "void endnetgrent(void);"
  21 .PP
  22 .BI "int getnetgrent(char **" host ", char **" user ", char **" domain );
  23 .PP
  24 .BI "int getnetgrent_r(char **" host ", char **" user ","
  25 .BI "                  char **" domain ", char *" buf ", size_t " buflen );
  26 .PP
  27 .BI "int innetgr(const char *" netgroup ", const char *" host ","
  28 .BI "            const char *" user ", const char *" domain );
  29 .fi
  30 .PP
  31 .in -4n
  32 Feature Test Macro Requirements for glibc (see
  33 .BR feature_test_macros (7)):
  34 .in
  35 .PP
  36 .ad l
  37 .BR setnetgrent (),
  38 .BR endnetgrent (),
  39 .BR getnetgrent (),
  40 .BR getnetgrent_r (),
  41 .BR innetgr ():
  42     Since glibc 2.19:
  43         _DEFAULT_SOURCE
  44     Glibc 2.19 and earlier:
  45         _BSD_SOURCE || _SVID_SOURCE
  46 .ad b
  47 .SH DESCRIPTION
  48 The
  49 .I netgroup
  50 is a SunOS invention.
  51 A netgroup database is a list of string triples
  52 .RI ( hostname ", " username ", " domainname )
  53 or other netgroup names.
  54 Any of the elements in a triple can be empty,
  55 which means that anything matches.
  56 The functions described here allow access to the netgroup databases.
  57 The file
  58 .I /etc/nsswitch.conf
  59 defines what database is searched.
  60 .PP
  61 The
  62 .BR setnetgrent ()
  63 call defines the netgroup that will be searched by subsequent
  64 .BR getnetgrent ()
  65 calls.
  66 The
  67 .BR getnetgrent ()
  68 function retrieves the next netgroup entry, and returns pointers in
  69 .IR host ,
  70 .IR user ,
  71 .IR domain .
  72 A null pointer means that the corresponding entry matches any string.
  73 The pointers are valid only as long as there is no call to other
  74 netgroup-related functions.
  75 To avoid this problem you can use the GNU function
  76 .BR getnetgrent_r ()
  77 that stores the strings in the supplied buffer.
  78 To free all allocated buffers use
  79 .BR endnetgrent ().
  80 .PP
  81 In most cases you want to check only if the triplet
  82 .RI ( hostname ", " username ", " domainname )
  83 is a member of a netgroup.
  84 The function
  85 .BR innetgr ()
  86 can be used for this without calling the above three functions.
  87 Again, a null pointer is a wildcard and matches any string.
  88 The function is thread-safe.
  89 .SH RETURN VALUE
  90 These functions return 1 on success and 0 for failure.
  91 .SH FILES
  92 .I /etc/netgroup
  93 .br
  94 .I /etc/nsswitch.conf
  95 .SH ATTRIBUTES
  96 For an explanation of the terms used in this section, see
  97 .BR attributes (7).
  98 .TS
  99 allbox;
 100 lbw16 lb lbw23
 101 l l l.
 102 Interface       Attribute       Value
 103 T{
 104 .BR setnetgrent (),
 105 .br
 106 .BR getnetgrent_r (),
 107 .br
 108 .BR innetgr ()
 109 T}      Thread safety   T{
 110 MT-Unsafe race:netgrent
 111 .br
 112 locale
 113 T}
 114 T{
 115 .BR endnetgrent ()
 116 T}      Thread safety   MT-Unsafe race:netgrent
 117 T{
 118 .BR getnetgrent ()
 119 T}      Thread safety   T{
 120 MT-Unsafe race:netgrent
 121 .br
 122 race:netgrentbuf locale
 123 T}
 124 .TE
 125 .sp 1
 126 In the above table,
 127 .I netgrent
 128 in
 129 .I race:netgrent
 130 signifies that if any of the functions
 131 .BR setnetgrent (),
 132 .BR getnetgrent_r (),
 133 .BR innetgr (),
 134 .BR getnetgrent (),
 135 or
 136 .BR endnetgrent ()
 137 are used in parallel in different threads of a program,
 138 then data races could occur.
 139 .SH CONFORMING TO
 140 These functions are not in POSIX.1, but
 141 .BR setnetgrent (),
 142 .BR endnetgrent (),
 143 .BR getnetgrent (),
 144 and
 145 .BR innetgr ()
 146 are available on most UNIX systems.
 147 .BR getnetgrent_r ()
 148 is not widely available on other systems.
 149 .\" getnetgrent_r() is on Solaris 8 and AIX 5.1, but not the BSDs.
 150 .SH NOTES
 151 In the BSD implementation,
 152 .BR setnetgrent ()
 153 returns void.
 154 .SH SEE ALSO
 155 .BR sethostent (3),
 156 .BR setprotoent (3),
 157 .BR setservent (3)