兄弟连区块链教程之以太坊源码分析CMD深入分析，2018年下半年，区块链行业正逐渐褪去发展之初的浮躁、回归理性，表面上看相关人才需求与身价似乎正在回落。但事实上，正是初期泡沫的渐退，让人们更多的关注点放在了区块链真正的技术之上。
### cmd包分析
#### cmd下面总共有13个子包，除了util包之外，每个子包都有一个主函数,每个主函数的init方法中都定义了该主函数支持的命令，如
##### geth包下面的：
```
func init() {
// Initialize the CLI app and start Geth
app.Action = geth
app.HideVersion = true // we have a command to print the version
app.Copyright = "Copyright 2013-2017 The go-ethereum Authors"
app.Commands = []cli.Command{
// See chaincmd.go:
initCommand,
importCommand,
exportCommand,
copydbCommand,
removedbCommand,
dumpCommand,
// See monitorcmd.go:
monitorCommand,
// See accountcmd.go:
accountCommand,
walletCommand,
// See consolecmd.go:
consoleCommand,
attachCommand,
javascriptCommand,
// See misccmd.go:
makecacheCommand,
makedagCommand,
versionCommand,
bugCommand,
licenseCommand,
// See config.go
dumpConfigCommand,
}
sort.Sort(cli.CommandsByName(app.Commands))
}
```
######再单独分析initCommand:
```
initCommand = cli.Command{
Action: utils.MigrateFlags(initGenesis),
Name: "init",
Usage: "Bootstrap and initialize a new genesis block",
ArgsUsage: "<genesisPath>",
Flags: []cli.Flag{
utils.DataDirFlag,
utils.LightModeFlag,
},
Category: "BLOCKCHAIN COMMANDS",
Description: `
The init command initializes a new genesis block and definition for the network.
This is a destructive action and changes the network in which you will be
participating.
```
######其中Name是对应命令的指令，action是调用该指令去完成的动作，usage表示用途,arguUsage显示该命令后面跟的参数个数以及每个参数的意义,
######该init方法其实就是去初始化创世块,flags代表的是这个子命令额外可以执行的命令,如改init命令可以携带两个参数，点进去utils.DataDirFlag可以看到：
```
// General settings
DataDirFlag = DirectoryFlag{
Name: "datadir",
Usage: "Data directory for the databases and keystore",
Value: DirectoryString{node.DefaultDataDir()},
}
```
* __可以用 --datadir [dir]来指定数据库的路径，如果没有指定由于该参数有value所以会启用默认的路径，也是home目录下面的.ethereum.__
* __/cmd/wnode/main.go 通过连接其他节点启动__
* __/cmd/geth /cmd/swarm 都是定义了很多命令__
### eth下cmd的rlpdump子包,该包的主要作用从给定文件中转储RLP数据以可读的形式．如果文件名被省略，数据将从stdin中读取
/rlpdump
#####解码rlp的数据
###### rlpdump的command的help
```
Usage: /tmp/___cmd_rlpdump_test [-noascii] [-hex <data>] [filename]
-hex string
dump given hex data
-noascii
don't print ASCII strings readably
-single
print only the first element, discard the rest
Dumps RLP data from the given file in readable form.
If the filename is omitted, data is read from stdin.
```
###### example1:
```
demo command: --hex f872f870845609a1ba64c0b8660480136e573eb81ac4a664f8f76e4887ba927f791a053ec5ff580b1037a8633320ca70f8ec0cdea59167acaa1debc07bc0a0b3a5b41bdf0cb4346c18ddbbd2cf222f54fed795dde94417d2e57f85a580d87238efc75394ca4a92cfe6eb9debcc3583c26fee8580
success_result_demo:
[
[
5609a1ba,
"d",
[],
0480136e573eb81ac4a664f8f76e4887ba927f791a053ec5ff580b1037a8633320ca70f8ec0cdea59167acaa1debc07bc0a0b3a5b41bdf0cb4346c18ddbbd2cf222f54fed795dde94417d2e57f85a580d87238efc75394ca4a92cfe6eb9debcc3583c26fee85,
"",
],
]
```
###### example2:
```
demo command: --noascii --hex CE0183FFFFFFC4C304050583616263
success_result_demo:
[
01,
ffffff,
[
[
04,
05,
05,
],
],
616263,
]
```
### cmd包下的p2psim子包的分析, p2psim is a command line client for the HTTP API
#####首先我们启动对应的main函数,对应的启动参数是`--help`,来查看该包下所有命令的使用,结果如下:
```
NAME:
___go_build_main_go__1_ - devp2p simulation command-line client
USAGE:
___go_build_main_go__1_ [global options] command [command options] [arguments...]
VERSION:
0.0.0
COMMANDS:
show show network information
events stream network events
snapshot create a network snapshot to stdout
load load a network snapshot from stdin
node manage simulation nodes
help, h Shows a list of commands or help for one command
GLOBAL OPTIONS:
--api value simulation API URL (default: "http://localhost:8888") [$P2PSIM_API_URL]
--help, -h show help
--version, -v print the version
```
#####该子包提供如何下的命令:
```
p2psim show
p2psim events [--current] [--filter=FILTER]
p2psim snapshot
p2psim load
p2psim node create [--name=NAME] [--services=SERVICES] [--key=KEY]
p2psim node list
p2psim node show <node>
p2psim node start <node>
p2psim node stop <node>
p2psim node connect <node> <peer>
p2psim node disconnect <node> <peer>
p2psim node rpc <node> <method> [<args>] [--subscribe]
```
#####要正常使用该子包下的命令，我们需要运行`/p2p/simulations/examples/ping-pong.go`的主函数来启动一个包含运行简单的节点的仿真网络.
正常启动后,你将看到:
```
INFO [01-23|11:17:10] using sim adapter
INFO [01-23|11:17:10] starting simulation server on 0.0.0.0:8888...
```
#####该服务启动后,提供如下的API,其作用等同于上面的命令,命令调用的实现其实就是调用API,访问的路径前缀就是`0.0.0.0:8888`:
```
GET / Get network information
POST /start Start all nodes in the network
POST /stop Stop all nodes in the network
GET /events Stream network events
GET /snapshot Take a network snapshot
POST /snapshot Load a network snapshot
POST /nodes Create a node
GET /nodes Get all nodes in the network
GET /nodes/:nodeid Get node information
POST /nodes/:nodeid/start Start a node
POST /nodes/:nodeid/stop Stop a node
POST /nodes/:nodeid/conn/:peerid Connect two nodes
DELETE /nodes/:nodeid/conn/:peerid Disconnect two nodes
GET /nodes/:nodeid/rpc Make RPC requests to a node via WebSocket
```
#####此处不深究API,仿真网络的服务已经起来了,下面开始p2psim包下命令的使用:
__/p2psim__
* show
```
function:显示当前仿真网络的状态
args:""
demo: show
notice:
success_result_demo:
NODES 0
CONNS 0
```
* snapshot
```
function:导出当前仿真网络的节点信息
args:""
demo: shapshot
notice:
success_result_demo:
{"nodes":[{"node":{"config":{"id":"085416957c3a0afef6aabe6c0d6b27b7cf8a61f28a3a5439010fcc9e49945a1818ea38946dda8c82004b231ab771450ee0d87886163b65eaa48ecfbcb85e871d","private_key":"3480d230f453e7c207bbd3b770bf774dc8a17e599394f9283147a35c3ead561c","name":"node1","services":["ping-pong"]},"up":true}},{"node":{"config":{"id":"cedbaecccfe42d04b742d1be6e924e0654a7eb1aa584d497f98d24951b156ada84bcfc6455ff37ba1fc81179d0a7c3da1ba34945be19d1fe5cd4c8a32a659a7b","private_key":"b7592cdeee6195c4486fcdd8007e1aedfd3a49e6c9f53e0845bf977d4ad043cc","name":"node2","services":["ping-pong"]},"up":false}}],"conns":[{"one":"cedbaecccfe42d04b742d1be6e924e0654a7eb1aa584d497f98d24951b156ada84bcfc6455ff37ba1fc81179d0a7c3da1ba34945be19d1fe5cd4c8a32a659a7b","other":"085416957c3a0afef6aabe6c0d6b27b7cf8a61f28a3a5439010fcc9e49945a1818ea38946dda8c82004b231ab771450ee0d87886163b65eaa48ecfbcb85e871d","up":false}]}
```
* node
> * create
```
function:创建一个节点
args:[--name=NAME] [--services=SERVICES] [--key=KEY]
demo: node create --name node1
notice:
success_result_demo:
Created node1
```
> * list
```
function:列出当前仿真网络的节点信息
args:""
demo: node list
notice:
success_result_demo:
NAME PROTOCOLS ID
node1 085416957c3a0afef6aabe6c0d6b27b7cf8a61f28a3a5439010fcc9e49945a1818ea38946dda8c82004b231ab771450ee0d87886163b65eaa48ecfbcb85e871d
node2 cedbaecccfe42d04b742d1be6e924e0654a7eb1aa584d497f98d24951b156ada84bcfc6455ff37ba1fc81179d0a7c3da1ba34945be19d1fe5cd4c8a32a659a7b
```
> * show
```
function:查看仿真网络中某个节点的具体信息
args:<node>
demo: node show node1
notice:
success_result_demo:
NAME node1
PROTOCOLS
ID 085416957c3a0afef6aabe6c0d6b27b7cf8a61f28a3a5439010fcc9e49945a1818ea38946dda8c82004b231ab771450ee0d87886163b65eaa48ecfbcb85e871d
ENODE enode://085416957c3a0afef6aabe6c0d6b27b7cf8a61f28a3a5439010fcc9e49945a1818ea38946dda8c82004b231ab771450ee0d87886163b65eaa48ecfbcb85e871d@127.0.0.1:30303
```
> * start
```
function:启动一个节点
args:<node>
demo: node start node1
notice:
success_result_demo:
Started node1
```
> * connect
```
function:将一个节点连接到另外一个节点
args:<node> <peer>
demo: node connect node2 node1
notice:
success_result_demo:
Connected node2 to node1
```
> * disconnect
```
function:节点断开连接
args:<node> <peer>
demo: node disconnect node2 node1
notice:
success_result_demo:
Disconnected node2 from node1
```
> * stop
```
function:停止一个节点
args:<node>
demo: node stop node2
notice:
success_result_demo:
Stopped node2
```
> * rpc
```
function:调用rpc接口
args:<node> <method> [<args>] [--subscribe]
demo: node rpc node1 admin
notice:
success_result_demo:
// TODO
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