logfile, err := os.OpenFile("./test.log", os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0666) if err != nil { panic("cannnot open test.log:" + err.Error()) } defer logfile.Close() // io.MultiWriteで、 // 標準出力とファイルの両方を束ねて、 // logの出力先に設定する log.SetOutput(io.MultiWriter(logfile, os.Stdout)) log.SetFlags(log.Ldate | log.Ltime) log.Println("Log!!")
![golangでlogを標準出力とテキストファイルの2箇所の出力する - Qiita](https://cdn-ak-scissors.b.st-hatena.com/image/square/e7d1b9782138475d39a0ec5b0b09054732b48ca3/height=288;version=1;width=512/https%3A%2F%2Fqiita-user-contents.imgix.net%2Fhttps%253A%252F%252Fcdn.qiita.com%252Fassets%252Fpublic%252Farticle-ogp-background-412672c5f0600ab9a64263b751f1bc81.png%3Fixlib%3Drb-4.0.0%26w%3D1200%26mark64%3DaHR0cHM6Ly9xaWl0YS11c2VyLWNvbnRlbnRzLmltZ2l4Lm5ldC9-dGV4dD9peGxpYj1yYi00LjAuMCZ3PTk3MiZoPTM3OCZ0eHQ9Z29sYW5nJUUzJTgxJUE3bG9nJUUzJTgyJTkyJUU2JUE4JTk5JUU2JUJBJTk2JUU1JTg3JUJBJUU1JThBJTlCJUUzJTgxJUE4JUUzJTgzJTg2JUUzJTgyJUFEJUUzJTgyJUI5JUUzJTgzJTg4JUUzJTgzJTk1JUUzJTgyJUExJUUzJTgyJUE0JUUzJTgzJUFCJUUzJTgxJUFFMiVFNyVBRSU4NyVFNiU4OSU4MCVFMyU4MSVBRSVFNSU4NyVCQSVFNSU4QSU5QiVFMyU4MSU5OSVFMyU4MiU4QiZ0eHQtYWxpZ249bGVmdCUyQ3RvcCZ0eHQtY29sb3I9JTIzMjEyMTIxJnR4dC1mb250PUhpcmFnaW5vJTIwU2FucyUyMFc2JnR4dC1zaXplPTU2JnM9N2JmOWQzZTg5M2Q5OWJjZDk1M2Y4M2ZjMWUwNmIzMWQ%26mark-x%3D142%26mark-y%3D57%26blend64%3DaHR0cHM6Ly9xaWl0YS11c2VyLWNvbnRlbnRzLmltZ2l4Lm5ldC9-dGV4dD9peGxpYj1yYi00LjAuMCZoPTc2Jnc9NzcwJnR4dD0lNDA3NHRoJnR4dC1jb2xvcj0lMjMyMTIxMjEmdHh0LWZvbnQ9SGlyYWdpbm8lMjBTYW5zJTIwVzYmdHh0LXNpemU9MzYmdHh0LWFsaWduPWxlZnQlMkN0b3Amcz1jZDM2M2Q4Y2NhMGE2ZDQ1ZmQ5Mjk3NzA0ODc3ZjE0Yg%26blend-x%3D142%26blend-y%3D486%26blend-mode%3Dnormal%26s%3D792f86c36042a1772a2f5be16f630aa0)