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GETPROTOENT(3)           BSD Library Functions Manual           GETPROTOENT(3)

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

LIBRARY
     Standard C Library (libc, -lc)

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(), getprotobyname(), and getprotobynumber() functions each return a pointer to an
     object with the following structure containing the broken-out fields of a line in the network protocol
     data base, /etc/protocols.

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

     The members of this structure are:

     p_name     The official name of the protocol.

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

     p_proto    The protocol number.

     The getprotoent() function reads the next line of the file, opening the file if necessary.

     The setprotoent() function opens and rewinds the file.  If the stayopen flag is non-zero, the net data
     base will not be closed after each call to getprotobyname() or getprotobynumber().

     The endprotoent() function closes the file.

     The getprotobyname() function and getprotobynumber() sequentially search from the beginning of the file
     until a matching protocol name or protocol number is found, or until EOF is encountered.

RETURN VALUES
     Null pointer (0) returned on EOF or error.

FILES
     /etc/protocols

SEE ALSO
     protocols(5)

HISTORY
     The getprotoent(), getprotobynumber(), getprotobyname(), setprotoent(), and endprotoent() functions
     appeared in 4.2BSD.

BUGS
     These functions use a thread-specific data space; if the data is needed for future use, it should be
     copied before any subsequent calls overwrite it.  Only the Internet protocols are currently understood.

BSD                              June 4, 1993                              BSD