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GETSERVENT(3) Linux Programmer's Manual GETSERVENT(3)
NAME
getservent, getservbyname, getservbyport, setservent, endservent - get service entry
SYNOPSIS
#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);
DESCRIPTION
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.
RETURN VALUE
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.
FILES
/etc/services
services database file
ATTRIBUTES
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(), endservent() │ Thread safety │ MT-Unsafe race:servent 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.
CONFORMING TO
POSIX.1-2001, POSIX.1-2008, 4.3BSD.
SEE ALSO
getnetent(3), getprotoent(3), getservent_r(3), services(5)
GNU 2021-03-22 GETSERVENT(3)