1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
|
// 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"
"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")
}
|
