ethkey: Added --stdoutkeystore parameter to avoid I/O operations

cmd/ethkey/README.md

@@ -13,6 +13,8 @@ If you want to use an existing private key to use in the keyfile, it can be
 specified by setting `--privatekey` with the location of the file containing the 
 private key.
 
+`--stdoutkeystore` option is available to avoid writing the keystore to file and
+instead output and entire contents of the keystore to standard output (stdout).
 
 ### `ethkey inspect <keyfile>`
 
@@ -39,3 +41,8 @@ For every command that uses a keyfile, you will be prompted to provide the
 passphrase for decrypting the keyfile.  To avoid this message, it is possible
 to pass the passphrase by using the `--passphrase` flag pointing to a file that
 contains the passphrase.
+
+## JSON
+
+For every command with output, the `--json` option is available to output JSON
+instead of human-readable format.

cmd/ethkey/generate.go

@@ -52,8 +52,28 @@ If you want to encrypt an existing private key, it can be specified by setting
 			Name:  "privatekey",
 			Usage: "file containing a raw private key to encrypt",
 		},
+		cli.BoolFlag{
+			Name:  "stdoutkeystore",
+			Usage: "prevents writing keystore to file, instead outputs the keystore to standard output (stdout)",
+		},
 	},
 	Action: func(ctx *cli.Context) error {
+		if ctx.Bool("stdoutkeystore") {
+			// Generate and output the keystore
+			_, keyjson := newKeyStore(ctx)
+			fmt.Printf("%s\n", keyjson)
+		} else {
+			// Generate and write keystore to file
+			storeKeyStore(ctx)
+		}
+
+		return nil
+	},
+}
+
+// storeKeyStore creates and stores a keystore from given parameters.
+// exits the program with an error message on failure.
+func storeKeyStore(ctx *cli.Context) {
 	// Check if keyfile path given and make sure it doesn't already exist.
 	keyfilepath := ctx.Args().First()
 	if keyfilepath == "" {
@@ -65,6 +85,29 @@ If you want to encrypt an existing private key, it can be specified by setting
 		utils.Fatalf("Error checking if keyfile exists: %v", err)
 	}
 
+	key, keyjson := newKeyStore(ctx)
+
+	if err := os.MkdirAll(filepath.Dir(keyfilepath), 0700); err != nil {
+		utils.Fatalf("Could not create directory %s", filepath.Dir(keyfilepath))
+	}
+	if err := ioutil.WriteFile(keyfilepath, keyjson, 0600); err != nil {
+		utils.Fatalf("Failed to write keyfile to %s: %v", keyfilepath, err)
+	}
+
+	// Output some information.
+	out := outputGenerate{
+		Address: key.Address.Hex(),
+	}
+	if ctx.Bool(jsonFlag.Name) {
+		mustPrintJSON(out)
+	} else {
+		fmt.Println("Address:", out.Address)
+	}
+}
+
+// newKeyStore outputs a new key and keystore from given parameters
+// exits the program with an error message on failure.
+func newKeyStore(ctx *cli.Context) (*keystore.Key, []byte) {
 	var privateKey *ecdsa.PrivateKey
 	var err error
 	if file := ctx.String("privatekey"); file != "" {
@@ -96,23 +139,5 @@ If you want to encrypt an existing private key, it can be specified by setting
 		utils.Fatalf("Error encrypting key: %v", err)
 	}
 
-		// Store the file to disk.
+	return key, keyjson
-		if err := os.MkdirAll(filepath.Dir(keyfilepath), 0700); err != nil {
-			utils.Fatalf("Could not create directory %s", filepath.Dir(keyfilepath))
-		}
-		if err := ioutil.WriteFile(keyfilepath, keyjson, 0600); err != nil {
-			utils.Fatalf("Failed to write keyfile to %s: %v", keyfilepath, err)
-		}
-
-		// Output some information.
-		out := outputGenerate{
-			Address: key.Address.Hex(),
-		}
-		if ctx.Bool(jsonFlag.Name) {
-			mustPrintJSON(out)
-		} else {
-			fmt.Println("Address:", out.Address)
-		}
-		return nil
-	},
 }