Add 03.2 - log package

parsiya · Dec 26, 2017 · cdbf68e · cdbf68e
1 parent 86f9e07
commit cdbf68e
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Showing 11 changed files with 445 additions and 7 deletions.
diff --git a/README.md b/README.md
@@ -15,7 +15,8 @@ These documents are based on the `Gray/Black Hat Python/C#` series of books. I l
     + [02.6 - Goroutines and channels](content/02.6.md)
     + [02.7 - Error handling](content/02.7.md)
 - [03 - Useful Go packages - WIP](content/03.0.md)
-    + [03.1 - flag](content/03.1.md)
+    + [03.1 - flag package](content/03.1.md)
+    + [03.2 - log package](content/03.2.md)
 - [04- Go networking](content/04.0.md)
     + [04.1 - Basic TCP and UDP clients](content/04.1.md)
     + [04.2 - TCP servers](content/04.2.md)

diff --git a/code/03/03.2/03.2-01-basic-logging.go b/code/03/03.2/03.2-01-basic-logging.go
@@ -0,0 +1,14 @@
+package main
+
+import (
+	"log"
+)
+
+func main() {
+
+	a, b := 10, 20
+
+	log.Print("Use Print to log.")
+	log.Println("Ditto for Println.")
+	log.Printf("Use Printf and format strings. %d + %d = %d", a, b, a+b)
+}
diff --git a/code/03/03.2/03.2-02-log-file.go b/code/03/03.2/03.2-02-log-file.go
@@ -0,0 +1,27 @@
+package main
+
+import (
+	"log"
+	"os"
+)
+
+func main() {
+
+	// Create a file
+	logFile, err := os.Create("log1.txt")
+	if err != nil {
+		panic("Could not open file")
+	}
+
+	// Close the file after main returns
+	defer logFile.Close()
+
+	a, b := 10, 20
+
+	// We will not use the other options
+	myLog := log.New(logFile, "", 0)
+
+	myLog.Print("Use Print to log.")
+	myLog.Println("Ditto for Println.")
+	myLog.Printf("Use Printf and format strings. %d + %d = %d", a, b, a+b)
+}
diff --git a/code/03/03.2/03.2-03-log-multiple-files.go b/code/03/03.2/03.2-03-log-multiple-files.go
@@ -0,0 +1,47 @@
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"log"
+	"os"
+)
+
+func main() {
+
+	// Create a file
+	logFile, err := os.Create("log1.txt")
+	if err != nil {
+		panic("Could not open file")
+	}
+
+	// Close the file after main returns
+	defer logFile.Close()
+
+	// Create a second file
+	logFile2, err := os.Create("log2.txt")
+	if err != nil {
+		panic("Could not open file2")
+	}
+
+	defer logFile2.Close()
+
+	// Create a buffer
+	var buflog bytes.Buffer
+
+	multiW := io.MultiWriter(logFile, logFile2, &buflog, os.Stdout)
+
+	a, b := 10, 20
+
+	// Log to multiW
+	myLog := log.New(multiW, "", 0)
+
+	myLog.Print("Use Print to log.")
+	myLog.Println("Ditto for Println.")
+	myLog.Printf("Use Printf and format strings. %d + %d = %d", a, b, a+b)
+
+	// Print buffer
+	fmt.Println("Buffer:")
+	fmt.Println(buflog.String())
+}
diff --git a/code/03/03.2/03.2-04-log-flags.go b/code/03/03.2/03.2-04-log-flags.go
@@ -0,0 +1,19 @@
+package main
+
+import (
+	"log"
+	"os"
+)
+
+func main() {
+
+	a, b := 10, 20
+
+	// New logger will output to stdout with flags
+	// Only log date and file
+	myLog := log.New(os.Stdout, "", log.Ldate|log.Lshortfile)
+
+	myLog.Print("Use Print to log.")
+	myLog.Println("Ditto for Println.")
+	myLog.Printf("Use Printf and format strings. %d + %d = %d", a, b, a+b)
+}
diff --git a/code/03/03.2/03.2-05-log-prefix.go b/code/03/03.2/03.2-05-log-prefix.go
@@ -0,0 +1,19 @@
+package main
+
+import (
+	"log"
+	"os"
+)
+
+func main() {
+
+	a, b := 10, 20
+
+	// New logger will output to stdout with prefix "Log1: " and flags
+	// Note the space in prefix
+	myLog := log.New(os.Stdout, "Log1: ", log.Ldate|log.Lshortfile)
+
+	myLog.Print("Use Print to log.")
+	myLog.Println("Ditto for Println.")
+	myLog.Printf("Use Printf and format strings. %d + %d = %d", a, b, a+b)
+}
diff --git a/code/03/03.2/log1.txt b/code/03/03.2/log1.txt
@@ -0,0 +1,3 @@
+Use Print to log.
+Ditto for Println.
+Use Printf for format strings. 10 + 20 = 30
diff --git a/code/03/03.2/log2.txt b/code/03/03.2/log2.txt
@@ -0,0 +1,3 @@
+Use Print to log.
+Ditto for Println.
+Use Printf for format strings. 10 + 20 = 30
diff --git a/content/03.0.md b/content/03.0.md
@@ -3,5 +3,5 @@ This is where this repo is going to divert a bit from BH books. This section is
 
 As I move forward and learn more, I will return and add more tutorials here.
 
-- [03.1 - flag](03.1.md)
-
+- [03.1 - flag package](03.1.md): Parsing command line parameters.
+- [03.2 - log package](03.2.md): Logging.
diff --git a/content/03.1.md b/content/03.1.md
@@ -1,4 +1,4 @@
-# flag
+# flag package
 [flag package][flag-pkg] is the Go equivalent of Python [argparse][python-argparse]. While not as powerful, it does what we expect it to do. It simplifies adding and parsing command line parameters, leaving us to concentrate on the tools. Most of our tools will need them to be actually useful (hardcoding URLs and IPs get old too fast).
 
 <!-- MarkdownTOC -->
@@ -510,10 +510,10 @@ As you can see there's a lot of manual work in sub commands and they are not as
 
 <!-- Links -->
 
-[flag-pkg]: https://golang.org/pkg/flag/
+[flag-pkg]: https://godoc.org/flag
 [python-argparse]: https://docs.python.org/2/howto/argparse.html
-[flag-value-interface]: https://golang.org/pkg/flag/#Value
+[flag-value-interface]: https://godoc.org/flag#Value
 [sync-waitgroup]: 02.6.md#syncwaitgroup
-[flag-newflagset]: https://golang.org/pkg/flag/#NewFlagSet
+[flag-newflagset]: https://godoc.org/flag#NewFlagSet
 [cobra-github]: https://github.com/spf13/cobra
 [cli-github]: https://github.com/urfave/cli