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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-28 13:14:23 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-28 13:14:23 +0000
commit73df946d56c74384511a194dd01dbe099584fd1a (patch)
treefd0bcea490dd81327ddfbb31e215439672c9a068 /src/os/example_test.go
parentInitial commit. (diff)
downloadgolang-1.16-upstream.tar.xz
golang-1.16-upstream.zip
Adding upstream version 1.16.10.upstream/1.16.10upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/os/example_test.go')
-rw-r--r--src/os/example_test.go242
1 files changed, 242 insertions, 0 deletions
diff --git a/src/os/example_test.go b/src/os/example_test.go
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+// 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)
+ }
+}