How to use runInDir method of main Package

...74		return nil, err75	}76	return &pkg, nil77}78// runInDir writes the given program into the given dir, runs it there, and79// parses the output as a model.Package.80func runInDir(program []byte, dir string) (*model.Package, error) {81	// We use TempDir instead of TempFile so we can control the filename.82	tmpDir, err := ioutil.TempDir(dir, "gomock_reflect_")83	if err != nil {84		return nil, err85	}86	defer func() {87		if err := os.RemoveAll(tmpDir); err != nil {88			log.Printf("failed to remove temp directory: %s", err)89		}90	}()91	const progSource = "prog.go"92	var progBinary = "prog.bin"93	if runtime.GOOS == "windows" {94		// Windows won't execute a program unless it has a ".exe" suffix.95		progBinary += ".exe"96	}97	if err := ioutil.WriteFile(filepath.Join(tmpDir, progSource), program, 0600); err != nil {98		return nil, err99	}100	cmdArgs := []string{}101	cmdArgs = append(cmdArgs, "build")102	if *buildFlags != "" {103		cmdArgs = append(cmdArgs, *buildFlags)104	}105	cmdArgs = append(cmdArgs, "-o", progBinary, progSource)106	// Build the program.107	cmd := exec.Command("go", cmdArgs...)108	cmd.Dir = tmpDir109	cmd.Stdout = os.Stdout110	cmd.Stderr = os.Stderr111	if err := cmd.Run(); err != nil {112		return nil, err113	}114	return run(filepath.Join(tmpDir, progBinary))115}116func reflect(importPath string, symbols []string) (*model.Package, error) {117	// TODO: sanity check arguments118	if *execOnly != "" {119		return run(*execOnly)120	}121	program, err := writeProgram(importPath, symbols)122	if err != nil {123		return nil, err124	}125	if *progOnly {126		os.Stdout.Write(program)127		os.Exit(0)128	}129	wd, _ := os.Getwd()130	// Try to run the program in the same directory as the input package.131	if p, err := build.Import(importPath, wd, build.FindOnly); err == nil {132		dir := p.Dir133		if p, err := runInDir(program, dir); err == nil {134			return p, nil135		}136	}137	// Since that didn't work, try to run it in the current working directory.138	if p, err := runInDir(program, wd); err == nil {139		return p, nil140	}141	// Since that didn't work, try to run it in a standard temp directory.142	return runInDir(program, "")143}144type reflectData struct {145	ImportPath string146	Symbols    []string147}148// This program reflects on an interface value, and prints the149// gob encoding of a model.Package to standard output.150// JSON doesn't work because of the model.Type interface.151var reflectProgram = template.Must(template.New("program").Parse(`152package main153import (154	"encoding/gob"155	"flag"156	"fmt"...

...70	// We cannot run stringer in the current directory for the following reasons:71	// - Versions of Go earlier than Go 1.11, do not support absolute directories as a pattern.72	// - When the current directory is inside a go module, the path will not be considered73	//   a valid path to a package.74	err := runInDir(dir, stringer, "-type", "Const", ".")75	if err != nil {76		t.Fatal(err)77	}78	result, err := ioutil.ReadFile(output)79	if err != nil {80		t.Fatal(err)81	}82	if bytes.Contains(result, protectedConst) {83		t.Fatal("tagged variable appears in untagged run")84	}85	err = os.Remove(output)86	if err != nil {87		t.Fatal(err)88	}89	err = runInDir(dir, stringer, "-type", "Const", "-tags", "tag", ".")90	if err != nil {91		t.Fatal(err)92	}93	result, err = ioutil.ReadFile(output)94	if err != nil {95		t.Fatal(err)96	}97	if !bytes.Contains(result, protectedConst) {98		t.Fatal("tagged variable does not appear in tagged run")99	}100}101// buildStringer creates a temporary directory and installs stringer there.102func buildStringer(t *testing.T) (dir string, stringer string) {103	t.Helper()104	dir, err := ioutil.TempDir("", "stringer")105	if err != nil {106		t.Fatal(err)107	}108	stringer = filepath.Join(dir, "stringer.exe")109	err = run("go", "build", "-o", stringer)110	if err != nil {111		t.Fatalf("building stringer: %s", err)112	}113	return dir, stringer114}115// stringerCompileAndRun runs stringer for the named file and compiles and116// runs the target binary in directory dir. That binary will panic if the String method is incorrect.117func stringerCompileAndRun(t *testing.T, dir, stringer, typeName, fileName string) {118	t.Helper()119	t.Logf("run: %s %s\n", fileName, typeName)120	source := filepath.Join(dir, fileName)121	err := copy(source, filepath.Join("testdata", fileName))122	if err != nil {123		t.Fatalf("copying file to temporary directory: %s", err)124	}125	stringSource := filepath.Join(dir, typeName+"_string.go")126	// Run stringer in temporary directory.127	err = run(stringer, "-type", typeName, "-output", stringSource, source)128	if err != nil {129		t.Fatal(err)130	}131	// Run the binary in the temporary directory.132	err = run("go", "run", stringSource, source)133	if err != nil {134		t.Fatal(err)135	}136}137// copy copies the from file to the to file.138func copy(to, from string) error {139	toFd, err := os.Create(to)140	if err != nil {141		return err142	}143	defer toFd.Close()144	fromFd, err := os.Open(from)145	if err != nil {146		return err147	}148	defer fromFd.Close()149	_, err = io.Copy(toFd, fromFd)150	return err151}152// run runs a single command and returns an error if it does not succeed.153// os/exec should have this function, to be honest.154func run(name string, arg ...string) error {155	return runInDir(".", name, arg...)156}157// runInDir runs a single command in directory dir and returns an error if158// it does not succeed.159func runInDir(dir, name string, arg ...string) error {160	cmd := exec.Command(name, arg...)161	cmd.Dir = dir162	cmd.Stdout = os.Stdout163	cmd.Stderr = os.Stderr164	return cmd.Run()165}...

1import (2func main() {3	fmt.Println("Hello World")4}5import (6func main() {7	fmt.Println("Hello World")8}9import (10func main() {11	fmt.Println("Hello World")12}13import (14func main() {15	fmt.Println("Hello World")16}17import (18func main() {19	fmt.Println("Hello World")20}21import (22func main() {23	fmt.Println("Hello World")24}25import (26func main() {27	fmt.Println("Hello World")28}29import (30func main() {31	fmt.Println("Hello World")32}33import (34func main() {35	fmt.Println("Hello World")36}37import (38func main() {39	fmt.Println("Hello World")40}41import (42func main() {43	fmt.Println("Hello World")44}45import (46func main() {47	fmt.Println("Hello World")48}49import (50func main() {51	fmt.Println("Hello World")52}

1import "fmt"2import "os/exec"3import "os"4func main() {5    out, err := exec.Command("ls").Output()6    if err != nil {7        fmt.Printf("%s", err)8    }9    fmt.Printf("%s", out)10    fmt.Println("Inside main")11    runInDir("ls", "/tmp")12}13func runInDir(command string, dir string) {14    fmt.Println("Inside runInDir")15    cmd := exec.Command(command)16    stdout, err := cmd.Output()17    if err != nil {18        fmt.Printf("%s", err)19    }20    fmt.Printf("%s", stdout)21}22In the above code, we have created a function runInDir() which takes two arguments command and dir. The function is responsible for executing the command in the given directory. The function is called from the main() function. The output of the above code is as follows:

1import (2func main() {3    wd, err := os.Getwd()4    if err != nil {5        fmt.Println(err)6    }7    err = os.MkdirAll(wd+"/test", 0777)8    if err != nil {9        fmt.Println(err)10    }11    f, err := os.Create(wd + "/test/test.txt")12    if err != nil {13        fmt.Println(err)14    }15    defer f.Close()16    _, err = f.WriteString("Hello World!")17    if err != nil {18        fmt.Println(err)19    }20    err = os.MkdirAll(wd+"/test/test1", 0777)21    if err != nil {22        fmt.Println(err)23    }24    f, err = os.Create(wd + "/test/test1/test1.txt")25    if err != nil {26        fmt.Println(err)27    }28    defer f.Close()29    _, err = f.WriteString("Hello World!")30    if err != nil {31        fmt.Println(err)32    }33    err = os.MkdirAll(wd+"/test/test2", 0777)34    if err != nil {35        fmt.Println(err)36    }37    f, err = os.Create(wd + "/test/test2/test2.txt")38    if err != nil {39        fmt.Println(err)40    }41    defer f.Close()42    _, err = f.WriteString("Hello World!")43    if err != nil {44        fmt.Println(err)45    }46    err = os.MkdirAll(wd+"/test/test3", 0777)47    if err != nil {48        fmt.Println(err)49    }50    f, err = os.Create(wd + "/test/test3/test3.txt")51    if err != nil {

1import (2func main() {3    cmd := exec.Command("ls")4    err := cmd.Run()5    if err != nil {6        fmt.Println(err)7    }8}9import (10func main() {11    cmd := exec.Command("ls")12    err := cmd.Run()13    if err != nil {14        fmt.Println(err)15    }16}

1import (2func main() {3    fmt.Println("Current working dir: ", os.Getwd())4    os.Chdir("/home/user1")5    fmt.Println("Current working dir: ", os.Getwd())6    os.Chdir("/home/user2")7    fmt.Println("Current working dir: ", os.Getwd())8}

1import (2func main() {3    path, _ = filepath.Abs("./")4    path = strings.Replace(path, "\\", "/", -1)5    fmt.Println(path)6    runInDir(path, "go", "run", "main.go")7}8func runInDir(dir, name string, arg ...string) {9    cmd := exec.Command(name, arg...)10    cmd.Run()11}12import (13func main() {14    path, _ = filepath.Abs("./")15    path = strings.Replace(path, "\\", "/", -1)16    fmt.Println(path)17    runInDir(path, "go", "run", "main.go")18}19func runInDir(dir, name string, arg ...string) {20    cmd := exec.Command(name, arg...)21    cmd.Run()22}23import (24func main() {25    path, _ = filepath.Abs("./")26    path = strings.Replace(path, "\\", "/", -1)27    fmt.Println(path)28    runInDir(path, "go", "run", "main.go")29}30func runInDir(dir, name string, arg ...string) {31    cmd := exec.Command(name, arg...)32    cmd.Run()33}34import (

1import (2func main() {3    runInDir("C:/Users/Ankit/Downloads", func() {4        files, _ := ioutil.ReadDir(".")5        for _, f := range files {6            fmt.Println(f.Name())7        }8    })9}10import (11func main() {12    runInDir("C:/Users/Ankit/Downloads", func() {13        files, _ := ioutil.ReadDir(".")14        for _, f := range files {15            fmt.Println(f.Name())16        }17    })18}19import (20func main() {21    runInDir("C:/Users/Ankit/Downloads", func() {22        files, _ := ioutil.ReadDir(".")23        for _, f := range files {24            fmt.Println(f.Name())25        }26    })27}28import (29func main() {30    runInDir("C:/Users/Ankit/Downloads", func() {31        files, _ := ioutil.ReadDir(".")32        for _, f := range files {33            fmt.Println(f.Name())34        }35    })36}37import (38func main() {39    runInDir("C:/Users/Ankit/Downloads", func() {40        files, _ := ioutil.ReadDir(".")41        for _, f := range files {42            fmt.Println(f.Name())43        }44    })45}46import (47func main() {48    runInDir("C:/Users/Ankit/Downloads", func() {49        files, _ := ioutil.ReadDir(".")50        for _, f := range files {

1import (2func main() {3	cmd := exec.Command("ls", "-l")4	out, err := cmd.CombinedOutput()5	if err != nil {6		fmt.Println(err)7	}8	fmt.Println(string(out))9}