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getprotobynumber(3)
NAME
  getprotobynumber, getprotobynumber_r - Get a protocol entry by number

SYNOPSIS
  #include <netdb.h>

  struct protoent *getprotobynumber(
	  int num );

  [Tru64 UNIX]	The following obsolete function is supported in order to
  maintain backward compatibility with previous versions of the operating
  system.  You should not use it in new designs.

  int getprotobynumber_r(
	  int num,
	  struct protoent *proto,
	  struct protoent_data *proto_data );

LIBRARY
  Standard C Library (libc)

STANDARDS
  Interfaces documented on this reference page conform to industry standards
  as follows:

  getprotobyname():  XNS4.0, XNS5.0

  Refer to the standards(5) reference page for more information about
  industry standards and associated tags.

PARAMETERS
  num Specifies the protocol number.

  proto
      [Tru64 UNIX]  For getprotobynumber_r() only, this points to the
      protoent structure.  The netdb.h header file defines the protoent
      structure.

  proto_data
      [Tru64 UNIX]  For getprotobynumber_r() only, this is data for the
      protocols database.  The netdb.h header file defines the protoent_data
      structure.

DESCRIPTION
  The getprotobynumber() function returns a pointer to a structure of type
  protoent. Its members specify data in fields from a record line in either
  the local /etc/protocols file or NIS distributed network protocols database
  file. To determine which file or files to search, and in which order, the
  system uses the switches in the /etc/svc.conf file. The netdb.h header file
  defines the protoent structure.

  The getprotobynumber() function searches the network protocols database
  file sequentially until a match with the num parameter occurs. The num
  parameter must specify the official protocol number. When EOF (End-Of-File)
  is reached without a match, a null pointer is returned by this function.

  When using the getprotobynumber() function, use the endprotoent() function
  to close the protocols file.

NOTES
  The getprotobynumber() function returns a pointer to thread-specific data.
  Subsequent calls to this or a related function from the same thread
  overwrite this data.

  [Tru64 UNIX]	The getprotobynumber_r() function is an obsolete reentrant
  version of the getprotobynumber() function.  It is supported in order to
  maintain backward compatibility with previous versions of the operating
  system and should not be used in new designs.	 Note that you must zero-fill
  the proto_data structure before its first access by either the
  setprotoent_r() or getprotobynumber_r() functions.

RETURN VALUES
  Upon successful completion, the getprotobynumber() function returns a
  pointer to a protoent structure.  If it fails or reaches the end of the
  network protocols database file, it returns a null pointer.

  [Tru64 UNIX]	Upon successful completion, the getprotobynumber_r() function
  stores the protoent structure in the location pointed to by proto, and
  returns a value of 0 (zero).	Upon failure, it returns a value of -1.

ERRORS
  Current industry standards do not define error values for the
  getprotobynumber() function.

  [Tru64 UNIX]	If any of the following conditions occurs, the
  getprotobynumber_r() function sets errno to the corresponding value:

  [EINVAL]
      The proto_data or proto parameter is invalid.

  [ESRCH]
      The search failed.

  In addition, if the getprotobynumber() or getprotobynumber_r() function
  fails to open the file, it sets errno to indicate the cause of the failure.

FILES
  /etc/protocols
      The Internet network protocols name database file. Each record in the
      file occupies a single line and has three fields: the official protocol
      name, the protocol number, and protocol aliases.

  /etc/svc.conf
      The database service selection configuration file.

SEE ALSO
  Functions: getprotobyname(3), getprotoent(3), setprotoent(3),
  endprotoent(3).

  Files: protocols(4), svc.conf(4).

  Networks: nis_intro(7).

  Standards: standards(5).

  Network Programmer's Guide

Index for Section 3

Alphabetical listing for G

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