GETPROTOENT Section: Linux Programmer's Manual (3) Updated: April 24, 2025 Index   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 BSD 4.3   SEE ALSO   Index NAME SYNOPSIS DESCRIPTION RETURN VALUE FILES CONFORMING TO SEE ALSO This document was created by using the manual pages. Time: 11:58:05 GMT, March 24, 2025