1 files changed, 242 insertions, 0 deletions
diff --git a/src/os/example_test.go b/src/os/example_test.go
new file mode 100644
index 0000000..3adce51
--- /dev/null
+++ b/src/os/example_test.go
@@ -0,0 +1,242 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package os_test
+
+import (
+	"fmt"
+	"io/fs"
+	"log"
+	"os"
+	"path/filepath"
+	"time"
+)
+
+func ExampleOpenFile() {
+	f, err := os.OpenFile("notes.txt", os.O_RDWR|os.O_CREATE, 0755)
+	if err != nil {
+		log.Fatal(err)
+	}
+	if err := f.Close(); err != nil {
+		log.Fatal(err)
+	}
+}
+
+func ExampleOpenFile_append() {
+	// If the file doesn't exist, create it, or append to the file
+	f, err := os.OpenFile("access.log", os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
+	if err != nil {
+		log.Fatal(err)
+	}
+	if _, err := f.Write([]byte("appended some data\n")); err != nil {
+		f.Close() // ignore error; Write error takes precedence
+		log.Fatal(err)
+	}
+	if err := f.Close(); err != nil {
+		log.Fatal(err)
+	}
+}
+
+func ExampleChmod() {
+	if err := os.Chmod("some-filename", 0644); err != nil {
+		log.Fatal(err)
+	}
+}
+
+func ExampleChtimes() {
+	mtime := time.Date(2006, time.February, 1, 3, 4, 5, 0, time.UTC)
+	atime := time.Date(2007, time.March, 2, 4, 5, 6, 0, time.UTC)
+	if err := os.Chtimes("some-filename", atime, mtime); err != nil {
+		log.Fatal(err)
+	}
+}
+
+func ExampleFileMode() {
+	fi, err := os.Lstat("some-filename")
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	fmt.Printf("permissions: %#o\n", fi.Mode().Perm()) // 0400, 0777, etc.
+	switch mode := fi.Mode(); {
+	case mode.IsRegular():
+		fmt.Println("regular file")
+	case mode.IsDir():
+		fmt.Println("directory")
+	case mode&fs.ModeSymlink != 0:
+		fmt.Println("symbolic link")
+	case mode&fs.ModeNamedPipe != 0:
+		fmt.Println("named pipe")
+	}
+}
+
+func ExampleIsNotExist() {
+	filename := "a-nonexistent-file"
+	if _, err := os.Stat(filename); os.IsNotExist(err) {
+		fmt.Println("file does not exist")
+	}
+	// Output:
+	// file does not exist
+}
+
+func ExampleExpand() {
+	mapper := func(placeholderName string) string {
+		switch placeholderName {
+		case "DAY_PART":
+			return "morning"
+		case "NAME":
+			return "Gopher"
+		}
+
+		return ""
+	}
+
+	fmt.Println(os.Expand("Good ${DAY_PART}, $NAME!", mapper))
+
+	// Output:
+	// Good morning, Gopher!
+}
+
+func ExampleExpandEnv() {
+	os.Setenv("NAME", "gopher")
+	os.Setenv("BURROW", "/usr/gopher")
+
+	fmt.Println(os.ExpandEnv("$NAME lives in ${BURROW}."))
+
+	// Output:
+	// gopher lives in /usr/gopher.
+}
+
+func ExampleLookupEnv() {
+	show := func(key string) {
+		val, ok := os.LookupEnv(key)
+		if !ok {
+			fmt.Printf("%s not set\n", key)
+		} else {
+			fmt.Printf("%s=%s\n", key, val)
+		}
+	}
+
+	os.Setenv("SOME_KEY", "value")
+	os.Setenv("EMPTY_KEY", "")
+
+	show("SOME_KEY")
+	show("EMPTY_KEY")
+	show("MISSING_KEY")
+
+	// Output:
+	// SOME_KEY=value
+	// EMPTY_KEY=
+	// MISSING_KEY not set
+}
+
+func ExampleGetenv() {
+	os.Setenv("NAME", "gopher")
+	os.Setenv("BURROW", "/usr/gopher")
+
+	fmt.Printf("%s lives in %s.\n", os.Getenv("NAME"), os.Getenv("BURROW"))
+
+	// Output:
+	// gopher lives in /usr/gopher.
+}
+
+func ExampleUnsetenv() {
+	os.Setenv("TMPDIR", "/my/tmp")
+	defer os.Unsetenv("TMPDIR")
+}
+
+func ExampleReadDir() {
+	files, err := os.ReadDir(".")
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	for _, file := range files {
+		fmt.Println(file.Name())
+	}
+}
+
+func ExampleMkdirTemp() {
+	dir, err := os.MkdirTemp("", "example")
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer os.RemoveAll(dir) // clean up
+
+	file := filepath.Join(dir, "tmpfile")
+	if err := os.WriteFile(file, []byte("content"), 0666); err != nil {
+		log.Fatal(err)
+	}
+}
+
+func ExampleMkdirTemp_suffix() {
+	logsDir, err := os.MkdirTemp("", "*-logs")
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer os.RemoveAll(logsDir) // clean up
+
+	// Logs can be cleaned out earlier if needed by searching
+	// for all directories whose suffix ends in *-logs.
+	globPattern := filepath.Join(os.TempDir(), "*-logs")
+	matches, err := filepath.Glob(globPattern)
+	if err != nil {
+		log.Fatalf("Failed to match %q: %v", globPattern, err)
+	}
+
+	for _, match := range matches {
+		if err := os.RemoveAll(match); err != nil {
+			log.Printf("Failed to remove %q: %v", match, err)
+		}
+	}
+}
+
+func ExampleCreateTemp() {
+	f, err := os.CreateTemp("", "example")
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer os.Remove(f.Name()) // clean up
+
+	if _, err := f.Write([]byte("content")); err != nil {
+		log.Fatal(err)
+	}
+	if err := f.Close(); err != nil {
+		log.Fatal(err)
+	}
+}
+
+func ExampleCreateTemp_suffix() {
+	f, err := os.CreateTemp("", "example.*.txt")
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer os.Remove(f.Name()) // clean up
+
+	if _, err := f.Write([]byte("content")); err != nil {
+		f.Close()
+		log.Fatal(err)
+	}
+	if err := f.Close(); err != nil {
+		log.Fatal(err)
+	}
+}
+
+func ExampleReadFile() {
+	data, err := os.ReadFile("testdata/hello")
+	if err != nil {
+		log.Fatal(err)
+	}
+	os.Stdout.Write(data)
+
+	// Output:
+	// Hello, Gophers!
+}
+
+func ExampleWriteFile() {
+	err := os.WriteFile("testdata/hello", []byte("Hello, Gophers!"), 0666)
+	if err != nil {
+		log.Fatal(err)
+	}
+}