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：
  1. func init() {
  2.     // Initialize the CLI app and start Geth
  3.     app.Action = geth
  4.     app.HideVersion = true // we have a command to print the version
  5.     app.Copyright = "Copyright 2013-2017 The go-ethereum Authors"
  6.     app.Commands = []cli.Command{
  7.         // See chaincmd.go:
  8.         initCommand,
  9.         importCommand,
  10.         exportCommand,
  11.         copydbCommand,
  12.         removedbCommand,
  13.         dumpCommand,
  14.         // See monitorcmd.go:
  15.         monitorCommand,
  16.         // See accountcmd.go:
  17.         accountCommand,
  18.         walletCommand,
  19.         // See consolecmd.go:
  20.         consoleCommand,
  21.         attachCommand,
  22.         javascriptCommand,
  23.         // See misccmd.go:
  24.         makecacheCommand,
  25.         makedagCommand,
  26.         versionCommand,
  27.         bugCommand,
  28.         licenseCommand,
  29.         // See config.go
  30.         dumpConfigCommand,
  31.     }
  32.     sort.Sort(cli.CommandsByName(app.Commands))
  33. }
再单独分析initCommand:
  1. initCommand = cli.Command{
  2.       Action:    utils.MigrateFlags(initGenesis),
  3.       Name:      "init",
  4.       Usage:     "Bootstrap and initialize a new genesis block",
  5.       ArgsUsage: "<genesisPath>",
  6.       Flags: []cli.Flag{
  7.          utils.DataDirFlag,
  8.          utils.LightModeFlag,
  9.       },
  10.       Category: "BLOCKCHAIN COMMANDS",
  11.       Description: `
  12. The init command initializes a new genesis block and definition for the network.
  13. This is a destructive action and changes the network in which you will be
  14. 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：
  1. // General settings
  2. DataDirFlag = DirectoryFlag{
  3.    Name:  "datadir",
  4.    Usage: "Data directory for the databases and keystore",
  5.    Value: DirectoryString{node.DefaultDataDir()},
  6. }

  • 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