setnetgrent(3)

1setnetgrent(3)             Library Functions Manual             setnetgrent(3)
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NAME

6       setnetgrent,  endnetgrent, getnetgrent, getnetgrent_r, innetgr - handle
7       network group entries
8

LIBRARY

10       Standard C library (libc, -lc)
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SYNOPSIS

13       #include <netdb.h>
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15       int setnetgrent(const char *netgroup);
16       void endnetgrent(void);
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18       int getnetgrent(char **restrict host,
19                   char **restrict user, char **restrict domain);
20       int getnetgrent_r(char **restrict host,
21                   char **restrict user, char **restrict domain,
22                   char buf[restrict .buflen], size_t buflen);
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24       int innetgr(const char *netgroup, const char *host,
25                   const char *user, const char *domain);
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27   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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29       setnetgrent(),    endnetgrent(),    getnetgrent(),     getnetgrent_r(),
30       innetgr():
31           Since glibc 2.19:
32               _DEFAULT_SOURCE
33           glibc 2.19 and earlier:
34               _BSD_SOURCE || _SVID_SOURCE
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DESCRIPTION

37       The  netgroup  is  a SunOS invention.  A netgroup database is a list of
38       string triples  (hostname,  username,  domainname)  or  other  netgroup
39       names.   Any of the elements in a triple can be empty, which means that
40       anything matches.  The functions described here  allow  access  to  the
41       netgroup  databases.  The file /etc/nsswitch.conf defines what database
42       is searched.
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44       The setnetgrent() call defines the netgroup that will  be  searched  by
45       subsequent  getnetgrent()  calls.  The getnetgrent() function retrieves
46       the next netgroup entry, and returns pointers in host, user, domain.  A
47       null  pointer  means  that  the corresponding entry matches any string.
48       The pointers are valid only as long as there is no call to  other  net‐
49       group-related  functions.   To  avoid  this problem you can use the GNU
50       function getnetgrent_r() that stores the strings in the  supplied  buf‐
51       fer.  To free all allocated buffers use endnetgrent().
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53       In  most  cases  you want to check only if the triplet (hostname, user‐
54       name, domainname) is a member of a netgroup.   The  function  innetgr()
55       can be used for this without calling the above three functions.  Again,
56       a null pointer is a wildcard and matches any string.  The  function  is
57       thread-safe.
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RETURN VALUE

60       These functions return 1 on success and 0 for failure.
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FILES

63       /etc/netgroup
64       /etc/nsswitch.conf
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ATTRIBUTES

67       For  an  explanation  of  the  terms  used  in  this  section,  see at‐
68       tributes(7).
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70       ┌─────────────────┬───────────────┬────────────────────────────────────┐
71       │Interface        │ Attribute     │ Value                              │
72       ├─────────────────┼───────────────┼────────────────────────────────────┤
73       │setnetgrent(),   │ Thread safety │ MT-Unsafe race:netgrent locale     │
74       │getnetgrent_r(), │               │                                    │
75       │innetgr()        │               │                                    │
76       ├─────────────────┼───────────────┼────────────────────────────────────┤
77       │endnetgrent()    │ Thread safety │ MT-Unsafe race:netgrent            │
78       ├─────────────────┼───────────────┼────────────────────────────────────┤
79       │getnetgrent()    │ Thread safety │ MT-Unsafe race:netgrent            │
80       │                 │               │ race:netgrentbuf locale            │
81       └─────────────────┴───────────────┴────────────────────────────────────┘
82       In  the above table, netgrent in race:netgrent signifies that if any of
83       the functions setnetgrent(), getnetgrent_r(), innetgr(), getnetgrent(),
84       or  endnetgrent()  are  used  in  parallel  in  different  threads of a
85       program, then data races could occur.
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VERSIONS

88       In the BSD implementation, setnetgrent() returns void.
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STANDARDS

91       None.
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HISTORY

94       setnetgrent(),  endnetgrent(),   getnetgrent(),   and   innetgr()   are
95       available   on  most  UNIX  systems.   getnetgrent_r()  is  not  widely
96       available on other systems.
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