getservent(3N) getservent(3N)
NAME
getservent, getservbyport, getservbyname, setservent,
endservent - get service entry
SYNOPSIS
#include <netdb.h>
struct servent *getservent()
struct servent *getservbyname(name, proto)
char *name, *proto;
struct servent *getservbyport(port, proto)
int port; char *proto;
setservent(stayopen)
int stayopen
endservent()
cc ... -lnet
DESCRIPTION
getservent, getservbyname, and getservbyport each return a
pointer to an object with the following structure containing
the broken-out fields of a line in the network services data
base, /etc/services.
struct servent {
char *s_name; /* official name of service */
char **s_aliases; /* alias list */
long s_port; /* port service resides at */
char *s_proto; /* protocol to use */
};
The members of this structure are:
sname The official name of the service.
saliases A zero terminated list of alternate names for the
service.
sport The port number at which the service resides.
Port numbers are returned in network byte order.
sproto The name of the protocol to use when contacting
the service.
getservent reads the next line of the file, opening the file
if necessary.
setservent opens and rewinds the file. If the stayopen flag
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getservent(3N) getservent(3N)
is non-zero, the net data base will not be closed after each
call to getservent (either directly, or indirectly through
one of the other ``getserv'' calls).
endservent closes the file.
getservbyname and getservbyport sequentially search from the
beginning of the file until a matching protocol name or port
number is found, or until EOF is encountered. If a protocol
name is also supplied (non-NULL), searches must also match
the protocol.
FILES
/etc/services
LINKING
This library is accessed by specifying -lnet as the last
argument to the compile line, e.g.:
cc -o prog prog.c -lnet
SEE ALSO
getprotoent(3N), services(4N).
DIAGNOSTICS
Null pointer (0) returned on EOF or error.
BUGS
All information is contained in a static area so it must be
copied if it is to be saved. Expecting port numbers to fit
in a 32 bit quantity is probably naive.
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