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Go Help

In this post, let us explore the options available with the Go tool.

pradeep@LearnGo example % go -h
Go is a tool for managing Go source code.

Usage:

	go <command> [arguments]

The commands are:

	bug         start a bug report
	build       compile packages and dependencies
	clean       remove object files and cached files
	doc         show documentation for package or symbol
	env         print Go environment information
	fix         update packages to use new APIs
	fmt         gofmt (reformat) package sources
	generate    generate Go files by processing source
	get         add dependencies to current module and install them
	install     compile and install packages and dependencies
	list        list packages or modules
	mod         module maintenance
	work        workspace maintenance
	run         compile and run Go program
	test        test packages
	tool        run specified go tool
	version     print Go version
	vet         report likely mistakes in packages

Use "go help <command>" for more information about a command.

Additional help topics:

	buildconstraint build constraints
	buildmode       build modes
	c               calling between Go and C
	cache           build and test caching
	environment     environment variables
	filetype        file types
	go.mod          the go.mod file
	gopath          GOPATH environment variable
	gopath-get      legacy GOPATH go get
	goproxy         module proxy protocol
	importpath      import path syntax
	modules         modules, module versions, and more
	module-get      module-aware go get
	module-auth     module authentication using go.sum
	packages        package lists and patterns
	private         configuration for downloading non-public code
	testflag        testing flags
	testfunc        testing functions
	vcs             controlling version control with GOVCS

Use "go help <topic>" for more information about that topic.

pradeep@LearnGo example %

We have been using go run so let us use help for that.

pradeep@LearnGo example % go help run
usage: go run [build flags] [-exec xprog] package [arguments...]

Run compiles and runs the named main Go package.
Typically the package is specified as a list of .go source files from a single
directory, but it may also be an import path, file system path, or pattern
matching a single known package, as in 'go run .' or 'go run my/cmd'.

If the package argument has a version suffix (like @latest or @v1.0.0),
"go run" builds the program in module-aware mode, ignoring the go.mod file in
the current directory or any parent directory, if there is one. This is useful
for running programs without affecting the dependencies of the main module.

If the package argument doesn't have a version suffix, "go run" may run in
module-aware mode or GOPATH mode, depending on the GO111MODULE environment
variable and the presence of a go.mod file. See 'go help modules' for details.
If module-aware mode is enabled, "go run" runs in the context of the main
module.

By default, 'go run' runs the compiled binary directly: 'a.out arguments...'.
If the -exec flag is given, 'go run' invokes the binary using xprog:
	'xprog a.out arguments...'.
If the -exec flag is not given, GOOS or GOARCH is different from the system
default, and a program named go_$GOOS_$GOARCH_exec can be found
on the current search path, 'go run' invokes the binary using that program,
for example 'go_js_wasm_exec a.out arguments...'. This allows execution of
cross-compiled programs when a simulator or other execution method is
available.

The exit status of Run is not the exit status of the compiled binary.

For more about build flags, see 'go help build'.
For more about specifying packages, see 'go help packages'.

See also: go build.
pradeep@LearnGo example % 

pradeep@LearnGo example % go list
example/hello

pradeep@LearnGo example % cat go.mod 
module example/hello

go 1.18

require rsc.io/quote v1.5.2

require (
	golang.org/x/text v0.0.0-20170915032832-14c0d48ead0c // indirect
	rsc.io/sampler v1.3.0 // indirect
)

pradeep@LearnGo example % cat go.sum 
golang.org/x/text v0.0.0-20170915032832-14c0d48ead0c h1:qgOY6WgZOaTkIIMiVjBQcw93ERBE4m30iBm00nkL0i8=
golang.org/x/text v0.0.0-20170915032832-14c0d48ead0c/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
rsc.io/quote v1.5.2 h1:w5fcysjrx7yqtD/aO+QwRjYZOKnaM9Uh2b40tElTs3Y=
rsc.io/quote v1.5.2/go.mod h1:LzX7hefJvL54yjefDEDHNONDjII0t9xZLPXsUe+TKr0=
rsc.io/sampler v1.3.0 h1:7uVkIFmeBqHfdjD+gZwtXXI+RODJ2Wc4O7MPEh/QiW4=
rsc.io/sampler v1.3.0/go.mod h1:T1hPZKmBbMNahiBKFy5HrXp6adAjACjK9JXDnKaTXpA=
pradeep@LearnGo example % 

pradeep@LearnGo example % go env 
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/pradeep/Library/Caches/go-build"
GOENV="/Users/pradeep/Library/Application Support/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOINSECURE=""
GOMODCACHE="/Users/pradeep/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="darwin"
GOPATH="/Users/pradeep/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/darwin_amd64"
GOVCS=""
GOVERSION="go1.18.1"
GCCGO="gccgo"
GOAMD64="v1"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/Users/pradeep/Go/example/go.mod"
GOWORK=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -arch x86_64 -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/cf/vzmh318x285f0c1sbsnm14m40000gn/T/go-build1994069254=/tmp/go-build -gno-record-gcc-switches -fno-common"
pradeep@LearnGo example %

pradeep@LearnGo example % go doc -h
Usage of [go] doc:
	go doc
	go doc <pkg>
	go doc <sym>[.<methodOrField>]
	go doc [<pkg>.]<sym>[.<methodOrField>]
	go doc [<pkg>.][<sym>.]<methodOrField>
	go doc <pkg> <sym>[.<methodOrField>]
For more information run
	go help doc

Flags:
  -all
    	show all documentation for package
  -c	symbol matching honors case (paths not affected)
  -cmd
    	show symbols with package docs even if package is a command
  -short
    	one-line representation for each symbol
  -src
    	show source code for symbol
  -u	show unexported symbols as well as exported
exit status 2
pradeep@LearnGo example % 

pradeep@LearnGo example % go doc fmt.Println
package fmt // import "fmt"

func Println(a ...any) (n int, err error)
    Println formats using the default formats for its operands and writes to
    standard output. Spaces are always added between operands and a newline is
    appended. It returns the number of bytes written and any write error
    encountered.

pradeep@LearnGo example %
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