ENDPROTOENT(3P) POSIX Programmer's Manual ENDPROTOENT(3P)PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the corresponding
Linux manual page for details of Linux behavior), or the interface may
not be implemented on Linux.
endprotoent, getprotobyname, getprotobynumber, getprotoent, setprotoent
— network protocol database functions
struct protoent *getprotobyname(const char *name);
struct protoent *getprotobynumber(int proto);
struct protoent *getprotoent(void);
void setprotoent(int stayopen);
These functions shall retrieve information about protocols. This infor‐
mation is considered to be stored in a database that can be accessed
sequentially or randomly. The implementation of this database is
The setprotoent() function shall open a connection to the database, and
set the next entry to the first entry. If the stayopen argument is non-
zero, the connection to the network protocol database shall not be
closed after each call to getprotoent() (either directly, or indirectly
through one of the other getproto*() functions), and the implementation
may maintain an open file descriptor for the database.
The getprotobyname() function shall search the database from the begin‐
ning and find the first entry for which the protocol name specified by
name matches the p_name member, opening and closing a connection to the
database as necessary.
The getprotobynumber() function shall search the database from the
beginning and find the first entry for which the protocol number speci‐
fied by proto matches the p_proto member, opening and closing a connec‐
tion to the database as necessary.
The getprotoent() function shall read the next entry of the database,
opening and closing a connection to the database as necessary.
The getprotobyname(), getprotobynumber(), and getprotoent() functions
shall each return a pointer to a protoent structure, the members of
which shall contain the fields of an entry in the network protocol
The endprotoent() function shall close the connection to the database,
releasing any open file descriptor.
These functions need not be thread-safe.
Upon successful completion, getprotobyname(), getprotobynumber(), and
getprotoent() return a pointer to a protoent structure if the requested
entry was found, and a null pointer if the end of the database was
reached or the requested entry was not found. Otherwise, a null
pointer is returned.
The application shall not modify the structure to which the return
value points, nor any storage areas pointed to by pointers within the
structure. The returned pointer, and pointers within the structure,
might be invalidated or the structure or the storage areas might be
overwritten by a subsequent call to getprotobyname(), getprotobynum‐
ber(), or getprotoent().
No errors are defined.
The following sections are informative.
The Base Definitions volume of POSIX.1‐2008, <netdb.h>
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
cal and Electronics Engineers, Inc and The Open Group. (This is
POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online
at http://www.unix.org/online.html .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the source
files to man page format. To report such errors, see https://www.ker‐
IEEE/The Open Group 2013 ENDPROTOENT(3P)