1ENDSERVENT(3P)             POSIX Programmer's Manual            ENDSERVENT(3P)
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PROLOG

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
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NAME

12       endservent, getservbyname, getservbyport, getservent, setservent — net‐
13       work services database functions
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SYNOPSIS

16       #include <netdb.h>
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18       void endservent(void);
19       struct servent *getservbyname(const char *name, const char *proto);
20       struct servent *getservbyport(int port, const char *proto);
21       struct servent *getservent(void);
22       void setservent(int stayopen);
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DESCRIPTION

25       These functions shall retrieve information about network services. This
26       information is considered to be  stored  in  a  database  that  can  be
27       accessed  sequentially or randomly. The implementation of this database
28       is unspecified.
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30       The setservent() function shall open a connection to the database,  and
31       set the next entry to the first entry. If the stayopen argument is non-
32       zero, the net database shall not be closed after each call to the  get‐
33       servent()  function  (either directly, or indirectly through one of the
34       other getserv*() functions), and the  implementation  may  maintain  an
35       open file descriptor for the database.
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37       The  getservent()  function  shall read the next entry of the database,
38       opening and closing a connection to the database as necessary.
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40       The getservbyname() function shall search the database from the  begin‐
41       ning  and  find the first entry for which the service name specified by
42       name matches the s_name member and the protocol name specified by proto
43       matches  the  s_proto  member,  opening and closing a connection to the
44       database as necessary.  If proto is a null pointer, any  value  of  the
45       s_proto member shall be matched.
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47       The  getservbyport() function shall search the database from the begin‐
48       ning and find the first entry for which  the  port  specified  by  port
49       matches  the  s_port  member  and  the protocol name specified by proto
50       matches the s_proto member, opening and closing  a  connection  to  the
51       database  as  necessary.   If proto is a null pointer, any value of the
52       s_proto member shall be matched. The port argument  shall  be  a  value
53       obtained by converting a uint16_t in network byte order to int.
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55       The  getservbyname(), getservbyport(), and getservent() functions shall
56       each return a pointer to a servent  structure,  the  members  of  which
57       shall contain the fields of an entry in the network services database.
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59       The  endservent() function shall close the database, releasing any open
60       file descriptor.
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62       These functions need not be thread-safe.
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RETURN VALUE

65       Upon successful completion, getservbyname(), getservbyport(), and  get‐
66       servent()  return  a  pointer  to  a servent structure if the requested
67       entry was found, and a null pointer if the  end  of  the  database  was
68       reached  or  the  requested  entry  was  not  found.  Otherwise, a null
69       pointer is returned.
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71       The application shall not modify the  structure  to  which  the  return
72       value  points,  nor any storage areas pointed to by pointers within the
73       structure. The returned pointer, and  pointers  within  the  structure,
74       might  be  invalidated  or  the structure or the storage areas might be
75       overwritten by a subsequent call to  getservbyname(),  getservbyport(),
76       or  getservent().  The returned pointer, and pointers within the struc‐
77       ture, might also be invalidated if the calling thread is terminated.
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ERRORS

80       No errors are defined.
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82       The following sections are informative.
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EXAMPLES

85       None.
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APPLICATION USAGE

88       The port argument of getservbyport() need not be  compatible  with  the
89       port values of all address families.
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RATIONALE

92       None.
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FUTURE DIRECTIONS

95       None.
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SEE ALSO

98       endhostent(), endprotoent(), htonl(), inet_addr()
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100       The Base Definitions volume of POSIX.1‐2017, <netdb.h>
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103       Portions  of  this text are reprinted and reproduced in electronic form
104       from IEEE Std 1003.1-2017, Standard for Information Technology --  Por‐
105       table  Operating System Interface (POSIX), The Open Group Base Specifi‐
106       cations Issue 7, 2018 Edition, Copyright (C) 2018 by the  Institute  of
107       Electrical  and  Electronics Engineers, Inc and The Open Group.  In the
108       event of any discrepancy between this version and the original IEEE and
109       The  Open Group Standard, the original IEEE and The Open Group Standard
110       is the referee document. The original Standard can be  obtained  online
111       at http://www.opengroup.org/unix/online.html .
112
113       Any  typographical  or  formatting  errors that appear in this page are
114       most likely to have been introduced during the conversion of the source
115       files  to  man page format. To report such errors, see https://www.ker
116       nel.org/doc/man-pages/reporting_bugs.html .
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120IEEE/The Open Group                  2017                       ENDSERVENT(3P)
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