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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | FILES | ATTRIBUTES | CONFORMING TO | SEE ALSO | COLOPHON |
GETSERVENT(3) Linux Programmer's Manual GETSERVENT(3)
getservent, getservbyname, getservbyport, setservent, endservent -
get service entry
#include <netdb.h>
struct servent *getservent(void);
struct servent *getservbyname(const char *name, const char *proto);
struct servent *getservbyport(int port, const char *proto);
void setservent(int stayopen);
void endservent(void);
The getservent() function reads the next entry from the services
database (see services(5)) and returns a servent structure containing
the broken-out fields from the entry. A connection is opened to the
database if necessary.
The getservbyname() function returns a servent structure for the
entry from the database that matches the service name using protocol
proto. If proto is NULL, any protocol will be matched. A connection
is opened to the database if necessary.
The getservbyport() function returns a servent structure for the
entry from the database that matches the port port (given in network
byte order) using protocol proto. If proto is NULL, any protocol
will be matched. A connection is opened to the database if
necessary.
The setservent() function opens a connection to the database, and
sets the next entry to the first entry. If stayopen is nonzero, then
the connection to the database will not be closed between calls to
one of the getserv*() functions.
The endservent() function closes the connection to the database.
The servent structure is defined in <netdb.h> as follows:
struct servent {
char *s_name; /* official service name */
char **s_aliases; /* alias list */
int s_port; /* port number */
char *s_proto; /* protocol to use */
}
The members of the servent structure are:
s_name The official name of the service.
s_aliases
A NULL-terminated list of alternative names for the service.
s_port The port number for the service given in network byte order.
s_proto
The name of the protocol to use with this service.
The getservent(), getservbyname() and getservbyport() functions
return a pointer to a statically allocated servent structure, or NULL
if an error occurs or the end of the file is reached.
/etc/services
services database file
For an explanation of the terms used in this section, see
attributes(7).
┌────────────────┬───────────────┬───────────────────────────┐
│Interface │ Attribute │ Value │
├────────────────┼───────────────┼───────────────────────────┤
│getservent() │ Thread safety │ MT-Unsafe race:servent │
│ │ │ race:serventbuf locale │
├────────────────┼───────────────┼───────────────────────────┤
│getservbyname() │ Thread safety │ MT-Unsafe race:servbyname │
│ │ │ locale │
├────────────────┼───────────────┼───────────────────────────┤
│getservbyport() │ Thread safety │ MT-Unsafe race:servbyport │
│ │ │ locale │
├────────────────┼───────────────┼───────────────────────────┤
│setservent(), │ Thread safety │ MT-Unsafe race:servent │
│endservent() │ │ locale │
└────────────────┴───────────────┴───────────────────────────┘
In the above table, servent in race:servent signifies that if any of
the functions setservent(), getservent(), or endservent() are used in
parallel in different threads of a program, then data races could
occur.
POSIX.1-2001, POSIX.1-2008, 4.3BSD.
getnetent(3), getprotoent(3), getservent_r(3), services(5)
This page is part of release 4.12 of the Linux man-pages project. A
description of the project, information about reporting bugs, and the
latest version of this page, can be found at
https://www.kernel.org/doc/man-pages/.
GNU 2016-10-08 GETSERVENT(3)
Pages that refer to this page: getent(1), byteorder(3), getaddrinfo(3), getnameinfo(3), getnetent(3), getprotoent(3), getservent_r(3), rexec(3), setnetgrent(3), nss(5), nsswitch.conf(5), services(5)