getprotoent(3)

1GETPROTOENT(3)             Linux Programmer's Manual            GETPROTOENT(3)
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NAME

6       getprotoent, getprotobyname, getprotobynumber, setprotoent, endprotoent
7       - get protocol entry
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SYNOPSIS

10       #include <netdb.h>
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12       struct protoent *getprotoent(void);
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14       struct protoent *getprotobyname(const char *name);
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16       struct protoent *getprotobynumber(int proto);
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18       void setprotoent(int stayopen);
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20       void endprotoent(void);
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DESCRIPTION

23       The getprotoent() function reads the  next  entry  from  the  protocols
24       database (see protocols(5)) and returns a protoent structure containing
25       the broken-out fields from the entry.  A connection is  opened  to  the
26       database if necessary.
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28       The  getprotobyname()  function  returns  a  protoent structure for the
29       entry from the database that matches the protocol name name.  A connec‐
30       tion is opened to the database if necessary.
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32       The  getprotobynumber()  function  returns a protoent structure for the
33       entry from the database that matches the  protocol  number  number.   A
34       connection is opened to the database if necessary.
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36       The setprotoent() function opens a connection to the database, and sets
37       the next entry to the first entry.  If stayopen is  nonzero,  then  the
38       connection  to  the database will not be closed between calls to one of
39       the getproto*() functions.
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41       The endprotoent() function closes the connection to the database.
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43       The protoent structure is defined in <netdb.h> as follows:
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45           struct protoent {
46               char  *p_name;       /* official protocol name */
47               char **p_aliases;    /* alias list */
48               int    p_proto;      /* protocol number */
49           }
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51       The members of the protoent structure are:
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53       p_name The official name of the protocol.
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55       p_aliases
56              A NULL-terminated list of alternative names for the protocol.
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58       p_proto
59              The protocol number.
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RETURN VALUE

62       The getprotoent(), getprotobyname()  and  getprotobynumber()  functions
63       return  a  pointer  to  a statically allocated protoent structure, or a
64       null pointer if an error occurs or the end of the file is reached.
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FILES

67       /etc/protocols
68              protocol database file
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ATTRIBUTES

71       For  an  explanation  of  the  terms  used   in   this   section,   see
72       attributes(7).
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74       ┌───────────────────┬───────────────┬──────────────────────────────┐
75       │Interface          │ Attribute     │ Value                        │
76       ├───────────────────┼───────────────┼──────────────────────────────┤
77       │getprotoent()      │ Thread safety │ MT-Unsafe race:protoent      │
78       │                   │               │ race:protoentbuf locale      │
79       ├───────────────────┼───────────────┼──────────────────────────────┤
80       │getprotobyname()   │ Thread safety │ MT-Unsafe race:protobyname   │
81       │                   │               │ locale                       │
82       ├───────────────────┼───────────────┼──────────────────────────────┤
83       │getprotobynumber() │ Thread safety │ MT-Unsafe race:protobynumber │
84       │                   │               │ locale                       │
85       ├───────────────────┼───────────────┼──────────────────────────────┤
86       │setprotoent(),     │ Thread safety │ MT-Unsafe race:protoent      │
87       │endprotoent()      │               │ locale                       │
88       └───────────────────┴───────────────┴──────────────────────────────┘
89       In  the above table, protoent in race:protoent signifies that if any of
90       the functions setprotoent(), getprotoent(), or endprotoent()  are  used
91       in  parallel  in  different threads of a program, then data races could
92       occur.
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CONFORMING TO

95       POSIX.1-2001, POSIX.1-2008, 4.3BSD.
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COLOPHON

101       This page is part of release 5.02 of the Linux  man-pages  project.   A
102       description  of  the project, information about reporting bugs, and the
103       latest    version    of    this    page,    can     be     found     at
104       https://www.kernel.org/doc/man-pages/.
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108GNU                               2017-09-15                    GETPROTOENT(3)