GETPROTOENT(3)

NAME
getprotoent, getprotobyname, getprotobynumber, setprotoent, endprotoent - get protocol entry

SYNOPSIS
#include <netdb.h>

struct protoent *getprotoent(void);

struct protoent *getprotobyname(const char *name);

struct protoent *getprotobynumber(int proto);

void setprotoent(int stayopen);

void endprotoent(void);

DESCRIPTION
The getprotoent() function reads the next line from the file /etc/protocols and returns a structure protoent containing the broken out fields from the line. The /etc/protocols file is opened if necessary.

The getprotobyname() function returns a protoent structure for the line from /etc/protocols that matches the protocol name name.

The getprotobynumber() function returns a protoent structure for the line that matches the protocol number number.

The setprotoent() function opens and rewinds the /etc/protocols file. If stayopen is true (1), then the file will not be closed between calls to getprotobyname() or getprotobynumber().

The endprotoent() function closes /etc/protocols.

The protoent structure is defined in <netdb.h> as follows:

struct protoent {
    char  *p_name;       /* official protocol name */
    char **p_aliases;    /* alias list */
    int    p_proto;      /* protocol number */
}

The members of the protoent structure are:

p_name
    The official name of the protocol.

p_aliases
    A zero terminated list of alternative names for the protocol.

p_proto
    The protocol number.

RETURN VALUE
The getprotoent(), getprotobyname() and getprotobynumber() functions return the protoent structure, or a NULL pointer if an error occurs or the end of the file is reached.

FILES
/etc/protocols
    protocol database file

CONFORMING TO
4.3BSD, POSIX.1-2001.

SEE ALSO
getnetent(3), getservent(3), protocols(5)