man3/getservent.3

   1 .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
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  12 .\" Since the Linux kernel and libraries are constantly changing, this
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  22 .\"
  23 .\" References consulted:
  24 .\"     Linux libc source code
  25 .\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
  26 .\"     386BSD man pages
  27 .\" Modified Sat Jul 24 19:19:11 1993 by Rik Faith (faith@cs.unc.edu)
  28 .\" Modified Wed Oct 18 20:23:54 1995 by Martin Schulze <joey@infodrom.north.de>
  29 .\" Modified Mon Apr 22 01:50:54 1996 by Martin Schulze <joey@infodrom.north.de>
  30 .\" 2001-07-25 added a clause about NULL proto (Martin Michlmayr or David N. Welton)
  31 .\"
  32 .TH GETSERVENT 3  2008-08-19 "GNU" "Linux Programmer's Manual"
  33 .SH NAME
  34 getservent, getservbyname, getservbyport, setservent, endservent \-
  35 get service entry
  36 .SH SYNOPSIS
  37 .nf
  38 .B #include <netdb.h>
  39 .sp
  40 .B struct servent *getservent(void);
  41 .sp
  42 .BI "struct servent *getservbyname(const char *" name ", const char *" proto );
  43 .sp
  44 .BI "struct servent *getservbyport(int " port ", const char *" proto );
  45 .sp
  46 .BI "void setservent(int " stayopen );
  47 .sp
  48 .B void endservent(void);
  49 .fi
  50 .SH DESCRIPTION
  51 The
  52 .BR getservent ()
  53 function reads the next entry from the services database (see
  54 .BR services (5))
  55 and returns a \fIservent\fP structure containing
  56 the broken-out fields from the entry.
  57 A connection is opened to the database if necessary.
  58 .PP
  59 The
  60 .BR getservbyname ()
  61 function returns a \fIservent\fP structure
  62 for the entry from the database
  63 that matches the service \fIname\fP using protocol \fIproto\fP.
  64 If \fIproto\fP is NULL, any protocol will be matched.
  65 A connection is opened to the database if necessary.
  66 .PP
  67 The
  68 .BR getservbyport ()
  69 function returns a \fIservent\fP structure
  70 for the entry from the database
  71 that matches the port \fIport\fP (given in network byte order)
  72 using protocol \fIproto\fP.
  73 If \fIproto\fP is NULL, any protocol will be matched.
  74 A connection is opened to the database if necessary.
  75 .PP
  76 The
  77 .BR setservent ()
  78 function opens a connection to the database,
  79 and sets the next entry to the first entry.
  80 If \fIstayopen\fP is nonzero,
  81 then the connection to the database
  82 will not be closed between calls to one of the
  83 .BR getserv* ()
  84 functions.
  85 .PP
  86 The
  87 .BR endservent ()
  88 function closes the connection to the database.
  89 .PP
  90 The \fIservent\fP structure is defined in \fI<netdb.h>\fP as follows:
  91 .sp
  92 .in +4n
  93 .nf
  94 struct servent {
  95     char  *s_name;       /* official service name */
  96     char **s_aliases;    /* alias list */
  97     int    s_port;       /* port number */
  98     char  *s_proto;      /* protocol to use */
  99 }
 100 .fi
 101 .in
 102 .PP
 103 The members of the \fIservent\fP structure are:
 104 .TP
 105 .I s_name
 106 The official name of the service.
 107 .TP
 108 .I s_aliases
 109 A NULL-terminated list of alternative names for the service.
 110 .TP
 111 .I s_port
 112 The port number for the service given in network byte order.
 113 .TP
 114 .I s_proto
 115 The name of the protocol to use with this service.
 116 .SH RETURN VALUE
 117 The
 118 .BR getservent (),
 119 .BR getservbyname ()
 120 and
 121 .BR getservbyport ()
 122 functions return a pointer to a
 123 statically allocated \fIservent\fP structure, or a NULL pointer if an
 124 error occurs or the end of the file is reached.
 125 .SH FILES
 126 .TP
 127 .I /etc/services
 128 services database file
 129 .SH CONFORMING TO
 130 4.3BSD, POSIX.1-2001.
 131 .SH SEE ALSO
 132 .BR getnetent (3),
 133 .BR getprotoent (3),
 134 .BR getservent_r (3),
 135 .BR services (5)