1GETSERVENT(3) Linux Programmer's Manual GETSERVENT(3)
2
6 getservent, getservbyname, getservbyport, setservent, endservent - get
7 service entry
8
10 #include <netdb.h>
11 struct servent *getservent(void);
13 struct servent *getservbyname(const char *name, const char *proto);
15 struct servent *getservbyport(int port, const char *proto);
16 void setservent(int stayopen);
18 void endservent(void);
19
21 The getservent() function reads the next entry from the services data‐
22 base (see services(5)) and returns a servent structure containing the
23 broken-out fields from the entry. A connection is opened to the data‐
24 base if necessary.
25 The getservbyname() function returns a servent structure for the entry
27 from the database that matches the service name using protocol proto.
28 If proto is NULL, any protocol will be matched. A connection is opened
29 to the database if necessary.
30 The getservbyport() function returns a servent structure for the entry
32 from the database that matches the port port (given in network byte or‐
33 der) using protocol proto. If proto is NULL, any protocol will be
34 matched. A connection is opened to the database if necessary.
35 The setservent() 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 getserv*() functions.
40 The endservent() function closes the connection to the database.
42 The servent structure is defined in <netdb.h> as follows:
44 struct servent {
46 char *s_name; /* official service name */
47 char **s_aliases; /* alias list */
48 int s_port; /* port number */
49 char *s_proto; /* protocol to use */
50 }
51 The members of the servent structure are:
53 s_name The official name of the service.
55 s_aliases
57 A NULL-terminated list of alternative names for the service.
58 s_port The port number for the service given in network byte order.
60 s_proto
62 The name of the protocol to use with this service.
63
65 The getservent(), getservbyname(), and getservbyport() functions return
66 a pointer to a statically allocated servent structure, or NULL if an
67 error occurs or the end of the file is reached.
68
70 /etc/services
71 services database file
72
74 For an explanation of the terms used in this section, see at‐
75 tributes(7).
76 ┌────────────────┬───────────────┬─────────────────────────────────────┐
78 │Interface │ Attribute │ Value │
79 ├────────────────┼───────────────┼─────────────────────────────────────┤
80 │getservent() │ Thread safety │ MT-Unsafe race:servent │
81 │ │ │ race:serventbuf locale │
82 ├────────────────┼───────────────┼─────────────────────────────────────┤
83 │getservbyname() │ Thread safety │ MT-Unsafe race:servbyname locale │
84 ├────────────────┼───────────────┼─────────────────────────────────────┤
85 │getservbyport() │ Thread safety │ MT-Unsafe race:servbyport locale │
86 ├────────────────┼───────────────┼─────────────────────────────────────┤
87 │setservent(), │ Thread safety │ MT-Unsafe race:servent locale │
88 │endservent() │ │ │
89 └────────────────┴───────────────┴─────────────────────────────────────┘
90 In the above table, servent in race:servent signifies that if any of
91 the functions setservent(), getservent(), or endservent() are used in
92 parallel in different threads of a program, then data races could oc‐
93 cur.
94
96 POSIX.1-2001, POSIX.1-2008, 4.3BSD.
97
99 getnetent(3), getprotoent(3), getservent_r(3), services(5)
100
102 This page is part of release 5.13 of the Linux man-pages project. A
103 description of the project, information about reporting bugs, and the
104 latest version of this page, can be found at
105 https://www.kernel.org/doc/man-pages/.
106GNU 2021-03-22 GETSERVENT(3)