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AIX Version 4.3 Communications Technical Reference, Volume 2

getprotoent Subroutine


Gets protocol entry from the /etc/protocols file.


Standard C Library (libc.a)


#include <netdb.h>
struct protoent *getprotoent ( )


Attention: Do not use the getprotoent subroutine in a multithreaded environment.

The getprotoent subroutine retrieves protocol information from the /etc/protocols file. An application program can use the getprotoent subroutine to access a protocol name, its aliases, and protocol number.

The getprotoent subroutine opens and performs a sequential read of the /etc/protocols file. The getprotoent subroutine returns a pointer to a protoent structure, which contains the fields for a line of information in the /etc/protocols file. The netdb.h file defines the protoent structure.

Use the endprotoent subroutine to close the /etc/protocols file.

Return Values

Upon successful completion, the getprotoent subroutine returns a pointer to a protoent structure.

Note: The return value points to static data that is overwritten by subsequent calls.

If an error occurs or the end of the file is reached, the getprotoent subroutine returns a null pointer.

Implementation Specifics

The getprotoent subroutine is part of Base Operating System (BOS) Runtime.

All applications containing the getprotoent subroutine must be compiled with _BSD set to a specific value. Acceptable values are 43 and 44. In addition, all socket applications must include the BSD libbsd.a library.


                          Contains protocol information.

Related Information

The endprotoent subroutine, getprotobyname subroutine, getprotobynumber subroutine, setprotoent subroutine.

Sockets Overview in AIX Version 4.3 Communications Programming Concepts.

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