Temporary files and directories sample

Followup on discussion in #243

examples/temporary-files-and-directories/temporary-files-and-directories.go

@@ -0,0 +1,65 @@
+// Throughout program execution, we often want to create
+// data that isn't needed after the program exits.
+// *Temporary files and directories* are useful for this
+// purpose since they don't pollute the file system over
+// time.
+
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+)
+
+func check(e error) {
+	if e != nil {
+		panic(e)
+	}
+}
+
+func main() {
+
+	// The easiest way to create a temporary file is by
+	// calling `ioutil.TempFile`. It creates a file *and*
+	// opens it for reading and writing. We provide `""`
+	// as the first argument, so `ioutil.TempFile` will
+	// create the file in the default location for our OS.
+	f, err := ioutil.TempFile("", "sample")
+	check(err)
+
+	// Display the name of the temporary file. On
+	// Unix-based OSes the directory will likely be `/tmp`.
+	// The file name starts with the prefix given as the
+	// second argument to `ioutil.TempFile` and the rest
+	// is chosen automatically to ensure that concurrent
+	// calls will always create different file names.
+	fmt.Println("Temp file name:", f.Name())
+
+	// Clean up the file after we're done. The OS is
+	// likely to clean up temporary files by itself after
+	// some time, but it's good practice to do this
+	// explicitly.
+	defer os.Remove(f.Name())
+
+	// We can write some data to the file.
+	_, err = f.Write([]byte{1, 2, 3, 4})
+	check(err)
+
+	// If we intend to write many temporary files, we may
+	// prefer to create a temporary *directory*.
+	// `ioutil.TempDir`'s arguments are the same as
+	// `TempFile`'s, but it returns a directory *name*
+	// rather than an open file.
+	dname, err := ioutil.TempDir("", "sampledir")
+	fmt.Println("Temp dir name:", dname)
+
+	defer os.RemoveAll(dname)
+
+	// Now we can synthesize temporary file names by
+	// prefixing them with our temporary directory.
+	fname := filepath.Join(dname, "file1")
+	err = ioutil.WriteFile(fname, []byte{1, 2}, 0666)
+	check(err)
+}

examples/temporary-files-and-directories/temporary-files-and-directories.hash

@@ -0,0 +1,2 @@
+5f7d0c43988d7dce235adb06ec02f4d2026b7f83
+pxE20wGTFjv

examples/temporary-files-and-directories/temporary-files-and-directories.sh

@@ -0,0 +1,4 @@
+# The exact names printed out will likely be different.
+$ go run temporary-files-and-directories.go
+Temp file name: /tmp/sample610887201
+Temp dir name: /tmp/sampledir898854668