Add cmdexec/withenv.go

Author: devlights

examples/basic/cmdexec/README.md

@@ -10,3 +10,4 @@
 |withcontext.go|cmdexec\_withcontext|コマンドを context.Context 付きで実行するサンプルです|
 |pipe.go|cmdexec\_pipe|(*Cmd).StdinPipe,StdoutPipe,StderrPipeのサンプルです|
 |multi\_command\_with\_pipe.go|cmdexec\_multi\_command\_with\_pipe|複数の (*exec.Cmd) をパイプストリームで繋いで実行するサンプルです|
+|withenv.go|cmdexec\_env|*exec.Cmd 実行時に追加の環境変数を指定するサンプルです|

examples/basic/cmdexec/examples.go

@@ -19,4 +19,5 @@ func (r *register) Regist(m mapping.ExampleMapping) {
 	m["cmdexec_withcontext"] = WithContext
 	m["cmdexec_pipe"] = Pipe
 	m["cmdexec_multi_command_with_pipe"] = MultiCommandWithPipe
+	m["cmdexec_env"] = WithEnv
 }

examples/basic/cmdexec/withenv.go

@@ -0,0 +1,59 @@
+package cmdexec
+
+import (
+	"errors"
+	"os"
+	"os/exec"
+	"runtime"
+
+	"github.com/devlights/gomy/output"
+)
+
+// WithEnv -- *exec.Cmd 実行時に追加の環境変数を指定するサンプルです.
+//
+// REFERENCES
+//  - https://dev.to/tobychui/quick-notes-for-go-os-exec-3ejg
+func WithEnv() error {
+	if runtime.GOOS == "windows" {
+		return errors.New("this example cannot run on Windows, sorry")
+	}
+
+	const (
+		Shell = "/bin/bash"
+	)
+
+	var (
+		cmd *exec.Cmd
+		out []byte
+		err error
+	)
+
+	//
+	// 環境変数の追加なし
+	//
+	cmd = exec.Command(Shell, "-c", "env | grep LANG")
+
+	out, err = cmd.Output()
+	if err != nil {
+		return err
+	}
+
+	output.Stdoutf("[no append]", "\n%s\n", out)
+	output.StdoutHr()
+
+	//
+	// 環境変数の追加あり
+	//
+	cmd = exec.Command(Shell, "-c", "env | grep LANG")
+	cmd.Env = append(os.Environ(), "LANG2=Japanese")
+
+	out, err = cmd.Output()
+	if err != nil {
+		return err
+	}
+
+	output.Stdoutf("[append   ]", "\n%s\n", out)
+	output.StdoutHr()
+
+	return nil
+}