Add Redirect File To Stdin During Delve Debug as a Go TIL

go/redirect-file-to-stdin-during-delve-debug.md

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+# Redirect File To Stdin During Delve Debug
+
+I have a go program that accepts input from stdin. The way I've been running
+the program as I develop it is to redirect the output of some sample files to
+the program.
+
+```bash
+$ go run . < sample/001.txt
+```
+
+When I then go to debug this program with
+[Delve](https://github.com/go-delve/delve), I'd still like to be able to
+redirect a file into the program to reproduce the exact behavior I'm seeing.
+
+The following won't work:
+
+```bash
+$ dlv debug . < samples/001.txt
+Stdin is not a terminal, use '-r' to specify redirects for the target process or --allow-non-terminal-interactive=true if you really want to specify a redirect for Delve
+```
+
+Fortunately, `dlv` sees what I'm trying to do and makes a recommendation. The
+`-r` flag can be used to specify redirects for the target process. The [`dlv`
+redirect
+docs](https://github.com/go-delve/delve/blob/master/Documentation/usage/dlv_redirect.md)
+explain that `-r` can be passed a `source:destination`. The `source` is `stdin`
+by default, but can also be `stdout` and `stderr`.
+
+I can redirect my file into the debugging session of my program like so:
+
+```bash
+$ dlv debug . -r stdin:samples/001.txt
+```
+
+Or even more succinctly:
+
+```bash
+$ dlv debug . -r samples/001.txt
+```