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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"
"log"
"os"
"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 {
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)
}
switch mode := fi.Mode(); {
case mode.IsRegular():
fmt.Println("regular file")
case mode.IsDir():
fmt.Println("directory")
case mode&os.ModeSymlink != 0:
fmt.Println("symbolic link")
case mode&os.ModeNamedPipe != 0:
fmt.Println("named pipe")
}
}
func ExampleIsNotExist() {
filename := "a-nonexistent-file"
if _, err := os.Stat(filename); os.IsNotExist(err) {
fmt.Printf("file does not exist")
}
// Output:
// file does not exist
}
func init() {
os.Setenv("USER", "gopher")
os.Setenv("HOME", "/usr/gopher")
os.Unsetenv("GOPATH")
}
func ExampleExpandEnv() {
fmt.Println(os.ExpandEnv("$USER lives in ${HOME}."))
// 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)
}
}
show("USER")
show("GOPATH")
// Output:
// USER=gopher
// GOPATH not set
}
func ExampleGetenv() {
fmt.Printf("%s lives in %s.\n", os.Getenv("USER"), os.Getenv("HOME"))
// Output:
// gopher lives in /usr/gopher.
}
func ExampleUnsetenv() {
os.Setenv("TMPDIR", "/my/tmp")
defer os.Unsetenv("TMPDIR")
}
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