Bitcoind

bitcoind is a program that implements the Bitcoin protocol for remote procedure call (RPC) use. It is also the second Bitcoin client in the network's history. It is available under the MIT license in 32-bit and 64-bit versions for Windows, GNU/Linux-based OSes, and Mac OS X.
As part of Bitcoin Core, bitcoind has been bundled with the original client from version 0.2.6 to 0.4.9, and with Bitcoin-Qt since 0.5.0.
=== Running ===
See running bitcoind for more detail and an example of the configuration file.
Bitcoind is a headless daemon, and also bundles a testing tool for the same daemon. It provides a JSON-RPC interface, allowing it to be controlled locally or remotely which makes it useful for integration with other software or in larger payment systems. Various commands are made available by the API.
To use locally, first start the program in daemon mode:
:bitcoind -daemon
Then you can execute API commands, e.g.:
:bitcoin-cli getinfo
:bitcoin-cli listtransactions
To stop the bitcoin daemon, execute:
:bitcoin-cli stop
==History of official bitcoind (and predecessor) releases==
Version 	Date 	Supported platforms 	Reference
0.16.0 	2018-Feb-26 	Windows32/64, Linux, ARM Linux, MacOS X	Bitcoin Core version 0.16.0 released
0.15.1 	2017-Nov-11 	Windows32/64, Linux, ARM Linux, MacOS X	Bitcoin Core version 0.15.1 released
0.15.0.1	2017-Sep-19 	Windows32/64, Linux, ARM Linux, MacOS X	Bitcoin Core version 0.15.0.1 released
0.15.0 	2017-Sep-14 	Windows32/64, Linux, ARM Linux, MacOS X	Bitcoin Core version 0.15.0 released
0.14.2 	2017-Jun-17 	Windows32/64, Linux, ARM Linux, MacOS X	Bitcoin Core version 0.14.2 released
0.14.1 	2017-Apr-22 	Windows32/64, Linux, ARM Linux, MacOS X	Bitcoin Core version 0.14.1 released
0.14.0 	2017-Mar-08 	Windows32/64, Linux, ARM Linux, MacOS X	Bitcoin Core version 0.14.0 released
0.13.2 	2017-Jan-03 	Windows32/64, Linux, ARM Linux, MacOS X	Bitcoin Core version 0.13.2 released
0.13.1 	2016-Oct-16 	Windows32/64, Linux, ARM Linux, MacOS X	Bitcoin Core version 0.13.1 released
0.13.0 	2016-Aug-23 	Windows32/64, Linux, ARM Linux, MacOS X	Bitcoin Core version 0.13.0 released
0.12.1 	2016-Apr-15 	Windows32/64, Linux, MacOS X 	Bitcoin Core version 0.12.1 released
0.12.0 	2016-Feb-23 	Windows32/64, Linux, MacOS X 	Bitcoin Core version 0.12.0 released
0.11.2 	2015-Nov-13 	Windows32/64, Linux, MacOS X 	Bitcoin Core version 0.11.2 released
0.11.1 	2015-Oct-15 	Windows32/64, Linux, MacOS X 	Bitcoin Core version 0.11.1 released
0.10.3 	2015-Oct-14 	Windows32/64, Linux, MacOS X 	Bitcoin Core version 0.10.3 released
0.11.0 	2015-Jul-12 	Windows32/64, Linux, MacOS X 	Bitcoin Core version 0.11.0 released
0.10.2 	2015-May-19 	Windows32/64, Linux, MacOS X 	Bitcoin Core version 0.10.2 released
0.10.1 	2015-Apr-27 	Windows32/64, Linux, MacOS X 	Bitcoin Core version 0.10.1 released
0.10.0 	2015-Feb-16 	Windows32/64, Linux, MacOS X 	Bitcoin Core version 0.10.0 released
0.9.3 	2014-Sep-27 	Windows32/64, Linux, MacOS X 	Bitcoin Core version 0.9.3 released
0.9.2.1 	2014-Jun-19 	Windows32/64, Linux, MacOS X 	Bitcoin Core version 0.9.2.1 released
0.9.2 	2014-Jun-16 	Windows32/64, Linux, MacOS X 	Bitcoin Core version 0.9.2 released
0.9.1 	2014-Apr-8 	Windows32/64, Linux, MacOS X 	Bitcoin Core version 0.9.1 released
0.9.0 	2014-Mar-19 	Windows32/64, Linux, MacOS X 	Bitcoin Core version 0.9.0 released
0.8.6 	2013-Dec-9 	Windows32, Linux, MacOS X 	Bitcoin-Qt version 0.8.6 released
0.8.5 	2013-Sep-13 	Windows32, Linux, MacOS X 	Bitcoin-Qt version 0.8.5 released
0.8.4 	2013-Sep-3 	Windows32, Linux, MacOS X 	Bitcoin-Qt version 0.8.4 released
0.8.3 	2013-Jun-25 	Windows32, Linux, MacOS X 	Bitcoin-Qt version 0.8.3 released
0.8.2 	2013-May-29 	Windows32, Linux, MacOS X 	Bitcoin-Qt version 0.8.2 released
0.8.1 	2013-Mar-18 	Windows32, Linux, MacOS X 	Bitcoin-Qt version 0.8.1 released
0.8.0 	2013-Feb-19 	Windows32, Linux, MacOS X 	Bitcoin-Qt version 0.8.0 released
0.7.2 	2012-Dec-14 	Windows32, Linux, MacOS X 	Bitcoin-Qt/bitcoind version 0.7.2 released
0.5.7 	2012-Nov-23 	 	
0.7.1 	2012-Oct-19 	Windows32, Linux, MacOS X 	Bitcoin-Qt/bitcoind version 0.7.1 released
0.7.0 	2012-Sep-17 	Windows32, Linux, MacOS X 	Bitcoin-Qt/bitcoind version 0.7.0 released
0.5.6 	2012-Jul-22 	Windows32, Linux, MacOS X 	
0.4.7 	2012-Jul-22 	Windows32 	
0.6.0.9 	2012-Jul-08 	 	
0.6.3 	2012-Jun-25 	Windows32, Linux, MacOS X 	Bitcoin-Qt / bitcoind version 0.6.3 released
0.6.2 	2012-May-08 	Windows32, Linux, MacOS X 	Re: Version 0.6.1 release candidate 2
0.6.1 	2012-May-04 	Windows32, Linux, MacOS X 	
0.6.0.7 	2012-May-04 	 	
0.5.5 	2012-May-04 	Windows32 	Version 0.5.5 and 0.4.6 released
0.4.6 	2012-May-04 	Windows32 	Version 0.5.5 and 0.4.6 released
0.5.4 	2012-Apr-15 	Windows32, Linux 	Version 0.5.4 released
0.4.5 	2012-Apr-15 	 	
0.6.0 	2012-Mar-30 	Windows32, Linux, MacOS X 	bitcoin.org: Bitcoin version 0.6.0 released
0.5.3.1 	2012-Mar-17 	Windows32 	URGENT: Windows Bitcoin-Qt update
0.5.3 	2012-Mar-14 	Windows32, Linux, MacOS X 	Bitcoin-Qt, bitcoind version 0.5.3 released
0.4.4 	2012-Mar-14 	Windows32 	bitcoind version 0.4.4 released
0.5.2 	2012-Jan-09 	Windows32, Linux, MacOS X 	Bitcoin-Qt, bitcoind version 0.5.2 released
0.4.3 	2012-Jan-09 	Windows32, Linux 	bitcoind version 0.4.3 released
0.5.1 	2011-Dec-15 	Windows32, Linux, MacOS X 	Bitcoin-Qt, bitcoind version 0.5.1 released
0.4.2 	2011-Dec-12 	 	
0.5.0 	2011-Nov-21 	Windows32, Linux, MacOS X 	Bitcoin-Qt/bitcoind version 0.5.0
0.4.1 	2011-Nov-21 	Windows32, Linux, MacOS X 	wxBitcoin/bitcoind version 0.4.1
0.4.0 	2011-Sep-23 	Windows32, Linux, MacOS X 	Bitcoin version 0.4.0 released
0.3.24 	2011-Jul-08 	Windows32, Linux, MacOS X 	Bitcoin version 0.3.24 released
0.3.23 	2011-Jun-13 	Windows32, Linux, MacOS X 	Bitcoin version 0.3.23 released
0.3.22 	2011-Jun-05 	Windows32, Linux, MacOS X 	Bitcoin version 0.3.22
0.3.21 	2011-Apr-27 	Windows32, Linux, MacOS X 	Bitcoin version 0.3.21
0.3.20 	2011-Feb-21 	Windows32, Linux, MacOS X 	Version 0.3.20
0.3.19 	2010-12-12 	Windows32, Linux, MacOS X 	Added some DoS limits, removed safe mode (0.3.19)
0.3.18 	2010-12-08 	Windows32, Linux, MacOS X 	Version 0.3.18
0.3.17 	2010-11-25 	Windows32, Linux, MacOS X 	Version 0.3.17
0.3.15 	2010-11-13 	Windows32, Linux 		Version 0.3.15
0.3.14 	2010-10-21 	Windows32, Linux 	Version 0.3.14
0.3.13 	2010-10-01 	Windows32, Linux, MacOS X 	Version 0.3.13, please upgrade
0.3.12 	2010-09-07 	Windows32, Linux 	Version 0.3.12 is now available.
0.3.11 	2010-08-27 	Windows32, Linux, MacOS X 	Version 0.3.11 is now available.
0.3.10 	2010-08-15 	Windows32, Linux32/64, MacOS X 	tcatm's 4-way SSE2 for Linux 32/64-bit is in 0.3.10
0.3.8.1 	2010-08-09 	Linux64 	Version 0.3.8.1 update for Linux 64-bit
0.3.8 	2010-08-03 	Windows32, Linux, MacOS X 	Please upgrade to 0.3.8!
0.3.7 	2010-08-01 	Windows32, Linux, MacOS X 	0.3.7 Changes
0.3.6 	2010-07-29 	Windows32, Linux, MacOS X 	*** ALERT *** Upgrade to 0.3.6
0.3.3 	2010-07-25 	Windows32, Linux, MacOS X 	Bitcoin 0.3.3 released -- PLEASE UPGRADE
0.3.2.5 	2010-07-24 	Windows32, Linux 	Version 0.3.2.5 -- please test!
0.3.2 	2010-07-17 	Windows32, Linux, MacOS X 	Bitcoin 0.3.2 released
0.3.1 	2010-07-15 	Windows32, Linux 	Bitcoin 0.3.1 released
0.3.0 	2010-07-06 	Windows32, Linux, MacOS X 	Bitcoin 0.3 released!Bitcoin 0.3 released!
0.2.0 	2009-12-17 06:52	Windows XP /Vista, Linux 	Bitcoin 0.2 released!Bitcoin 0.2 released
0.1.5 	2009-02-04 19:46	Windows NT/2000/XP 	Bitcoin v0.1.5 released
0.1.3 	2009-01-12 22:48	Windows NT/2000/XP 	Bitcoin v0.1.3
0.1.2 	2009-01-11 22:32	Windows NT/2000/XP 	Bitcoin v0.1.2 now available
0.1.0 	2009-01-09 	Windows NT/2000/XP 	
Up to and including version 0.3.19 is the "Satoshi code". The founder retired from development with end of 2010. Here are three URLs given where you still(!) (2013-01-04) can download one of the "original Satoshi codes". So also this Bitcoin release history.
==Theory of Operation==
bitcoind is a multithreaded C++ program. It is designed to be portable across Windows, Mac, and Linux systems. The multithreaded aspect leads to some complexity and the use of certain code patterns to deal with concurrency that may be unfamiliar to many programmers. Also, the code is aggressive in the use of C++ constructs, so it will help to be fluent with map, multimap, set, string, vector, iostream, and templates. As is typical of a C++ program, a lot of code tends to end up in the header files so be sure to search both the .cpp and .h files when looking for a function.
The client is oriented around several major operations, which are described in separate detailed articles and summarized in the following sections.
===Initialization and Startup===
Upon startup, the client performs various initialization routines including starting multiple threads to handle concurrent operations.
===Node Discovery===
The client uses various techniques to find out about other Bitcoin nodes that are currently connected to the network.
===Node Connectivity===
The client initiates and maintains connections to other nodes.
===Sockets and Messages===
The client processes messages from other nodes and sends messages to other nodes using socket connections.
===Block Exchange===
Nodes advertise their inventory of blocks to each other and exchange blocks to build block chains.
===Transaction Exchange===
Nodes exchange and relay transactions with each other. The client associates transactions with bitcoin addresses in the local wallet.
===Wallet Services===
The client can create transactions using the local wallet. The client associates transactions with bitcoin addresses in the local wallet. The client provides a service for managing the local wallet.
===RPC Interface===
The client offers an JSON-RPC interface over HTTP over sockets to perform various operational functions and to manage the local wallet.
===User Interface===
Bitcoind's current user interface is the command line while it used to be based on wxWidgets. A graphical user interface is now provided by Bitcoin-qt in version 0.5+ for the reference client.
==Troubleshooting==
===I get "Error loading blkindex.dat" when I try to run the client===
blkindex.dat is part of the database that stores the local copy of the blockchain which may have become corrupted. 
Open the Bitcoin data directory:
* Windows: %APPDATA%\Bitcoin
* Linux: ~/.bitcoin
* Mac: ~/Library/Application Support/Bitcoin/
Make a backup of that entire folder, then delete everything EXCEPT wallet.dat. Start bitcoin again and it will download a fresh copy of the blockchain (WARNING: This will take a long time).
==See Also==
* Original Bitcoin client/API calls list
* Bitcoin network protocol
* Development process
* Release process
* Changelog
==External Links==
* Bitcoin Core project on GitHub
==References==
`
es:Bitcoind
Category:Nodes
Category:Wallets
Category:User Interfaces
Category:Clients
Category:Developer
Category:Technical
Category:Free Software
Category:License/MIT-X11
Category:Open Source