1 files changed, 23 insertions(+), 0 deletions(-)

M content-org/content.org

@@ 5415,6 5415,29 @@ mkShell {
   haven't used none of them, there's nothing like [[https://doc.rust-lang.org/cargo/][cargo]] or [[https://www.npmjs.com/][npm]] with a
   public registry and standardized /manifest/.
 
+** Writing logs to multiple outputs in Go                               :go:
+:PROPERTIES:
+:EXPORT_DATE: 2023-07-19
+:EXPORT_FILE_NAME: writing-logs-to-multiple-outputs-in-go
+:EXPORT_HUGO_SLUG: writing-logs-to-multiple-outputs-in-go
+:END:
+
+The [[https://golang.org/pkg/io/#Writer][io.Writer]] interface is one of the most important interfaces in [[https://go.dev][Go]].
+We can take advantage of it to write logs to multiple places at the
+same time using the [[https://golang.org/pkg/io/#MultiWriter][io.MultiWriter]] function.
+
+For example, writing a log to the Standard Output ([[https://golang.org/pkg/os/#pkg-variables][os.Stdout]] and a
+file [[https://golang.org/pkg/os/#File][os.File]]) is pretty straightforward.
+
+#+begin_src go
+f, _ := os.Create("log.txt")
+defer f.Close()
+
+// our writer
+w := io.MultiWriter(os.Stdout, f)
+logger := log.New(w, "MultiWriter loggger", log.LstdFlags)
+#+end_src
+
 * Footnotes
 
 [fn:48] [[https://www.polyml.org/][Poly/ML]] exposes a function that does just that: [[https://www.polyml.org/documentation/Reference/PolyMLStructure.html#print][PolyML.print]].