105 lines
6.1 KiB
Markdown
105 lines
6.1 KiB
Markdown
#1.3 Go commands
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## Go commands
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Go language comes with a complete set of command operation tool, you can execute the command line `go` to see them:
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Figure 1.3 Go command displays detailed information
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These are all useful for us, let's see how to use some of them.
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## go build
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This command is for compiling tests, it will compile dependence packages if it's necessary.
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- If the package is not the `main` package such as `mymath` in section 1.2, nothing will be generated after you executed `go build`. If you need package file `.a` in `$GOPATH/pkg`, use `go install` instead.
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- If the package is the `main` package, it will generate an executable file in the same folder. If you want the file to be generated in `$GOPATH/bin`, use `go install` or `go build -o ${PATH_HERE}/a.exe.`
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- If there are many files in the folder, but you just want to compile one of them, you should append file name after `go build`. For example, `go build a.go`. `go build` will compile all the files in the folder.
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- You can also assign the name of file that will be generated. For instance, we have `mathapp` in section 1.2, use `go build -o astaxie.exe` will generate `astaxie.exe` instead of `mathapp.exe`. The default name is your folder name(non-main package) or the first source file name(main package).
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(According to [The Go Programming Language Specification](https://golang.org/ref/spec), package name should be the name after the word `package` in the first line of your source files, it doesn't have to be the same as folder's, and the executable file name will be your folder name as default.])
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- `go build` ignores files whose name starts with `_` or `.`.
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- If you want to have different source files for every operating system, you can name files with system name as suffix. Suppose there are some source files for loading arrays, they could be named as follows.
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array_linux.go | array_darwin.go | array_windows.go | array_freebsd.go
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`go build` chooses the one that associated with your operating system. For example, it only compiles array_linux.go in Linux systems, and ignores all the others.
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## go clean
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This command is for clean files that are generated by compilers, including following files.
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_obj/ // old directory of object, left by Makefiles
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_test/ // old directory of test, left by Makefiles
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_testmain.go // old directory of gotest, left by Makefiles
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test.out // old directory of test, left by Makefiles
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build.out // old directory of test, left by Makefiles
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*.[568ao] // object files, left by Makefiles
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DIR(.exe) // generated by go build
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DIR.test(.exe) // generated by go test -c
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MAINFILE(.exe) // generated by go build MAINFILE.go
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I usually use this command to clean my files before I upload my project to the Github, these are useful for local tests, but useless for version control.
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## go fmt
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The people who are working with C/C++ should know that people are always arguing about code style between K&R-style and ANSI-style, which one is better. However in Go, there is only one code style which is forced to use. For example, you must put left brace in the end of the line, and can't put it in a single line, otherwise you will get compile errors! Fortunately, you don't have to remember these rules, `go fmt` does this job for you, just execute command `go fmt <File name>.go` in terminal. I don't use this command very much because IDEs usually execute this command automatically when you save source files, I will talk about IDEs more in next section.
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We usually use `gofmt -w` instead of `go fmt`, the latter will not rewrite your source files after formatted code. `gofmt -w src` formats the whole project.
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## go get
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This command is for getting remote packages, it supports BitBucket, Github, Google Code, Launchpad so far. There are actually two things happening after we executed this command. The first thing is to download source code, then executes `go install`. Before you use this command, make sure you have installed related tools.
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BitBucket (Mercurial Git)
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Github (git)
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Google Code (Git, Mercurial, Subversion)
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Launchpad (Bazaar)
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In order to use this command, you have to install these tools correctly. Don't forget to set `PATH`. By the way, it also supports customized domain names, use `go help remote` for more details.
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## go install
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This command compiles all packages and generate files, then move them to `$GOPATH/pkg` or `$GOPATH/bin`.
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## go test
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This command loads all files whose name include `*_test.go` and generate test files, then prints information looks like follows.
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ok archive/tar 0.011s
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FAIL archive/zip 0.022s
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ok compress/gzip 0.033s
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...
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It tests all your test files as default, use command `go help testflag` for more details.
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## go doc
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Many people said that we don't need any third-party documentation for programming in Go(actually I've made a [CHM](https://github.com/astaxie/godoc) already), Go has a powerful tool to manage documentation by itself.
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So how to look up packages' information in documentation? If you want to get more details about package `builtin`, use command `go doc builtin`, and use command `go doc net/http` for package `http`. If you want to see more details about specific functions, use command `godoc fmt Printf`, and `godoc -src fmt Printf` to view source code.
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Execute command `godoc -http=:8080`, then open `127.0.0.1:8080` in your browsers, you should see a localized golang.org. It can not only show the standard packages' information, but also packages in your `$GOPATH/pkg`. It's great for people who are suffering from the Great Firewall of China.
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## Other commands
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Go provides more commands then I just talked about.
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go fix // upgrade code from old version before go1 to new version after go1
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go version // get information about Go version
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go env // view environment variables about Go
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go list // list all installed packages
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go run // compile temporary files and run the application
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There are also more details about commands that I talked about, you can use `go help <command>` to get more information.
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## Links
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- [Directory](preface.md)
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- Previous section: [$GOPATH and workspace](01.2.md)
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- Next section: [Go development tools](01.4.md)
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