84 lines
1.4 KiB
Go
84 lines
1.4 KiB
Go
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package files
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import (
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"bufio"
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"fmt"
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"io"
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"os"
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)
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func Files() {
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Reading()
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Writing()
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}
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func check(err error) {
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if err != nil {
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panic(err)
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}
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}
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func Reading() {
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data, err := os.ReadFile("/etc/hosts")
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check(err)
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fmt.Println("Contents:")
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fmt.Println(string(data))
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f, err := os.Open("/etc/hosts")
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defer f.Close()
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check(err)
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bytes1 := make([]byte, 5)
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n1, err := f.Read(bytes1)
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check(err)
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fmt.Printf("Read %d bytes: %v\n", n1, string(bytes1[:n1]))
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o1, err := f.Seek(5, 0)
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check(err)
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bytes2 := make([]byte, 4)
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n2, err := f.Read(bytes2)
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check(err)
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fmt.Printf("Read %d bytes @ %d: %v\n", n2, o1, string(bytes2[:n2]))
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o2, err := f.Seek(5, 0)
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check(err)
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bytes3 := make([]byte, 4)
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n3, err := io.ReadAtLeast(f, bytes3, 2)
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check(err)
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fmt.Printf("Read %d bytes @ %d: %v\n", n3, o2, string(bytes3))
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o3, err := f.Seek(5, 0)
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check(err)
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br := bufio.NewReader(f)
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bytes4, err := br.Peek(4)
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check(err)
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fmt.Printf("Read @ %d: %v\n", o3, string(bytes4))
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}
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func Writing() {
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err := os.WriteFile("/tmp/go.files.write.txt", []byte("hello go!"), 0600)
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check(err)
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f, err := os.Create("/tmp/go.files.write2.txt")
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check(err)
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n1, err := f.Write([]byte{87, 73, 78})
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check(err)
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fmt.Printf("Wrote %d bytes\n", n1)
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n2, err := f.WriteString(" macOS")
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check(err)
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fmt.Printf("Wrote %d bytes\n", n2)
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f.Sync()
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bw := bufio.NewWriter(f)
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n3, err := bw.WriteString(" linux")
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check(err)
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fmt.Printf("Wrote %d bytes\n", n3)
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bw.Flush()
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}
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