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

README.md

@@ -10,7 +10,7 @@ pairing with smart people at Hashrocket.
 
 For a steady stream of TILs, [sign up for my newsletter](https://crafty-builder-6996.ck.page/e169c61186).
 
-_1535 TILs and counting..._
+_1536 TILs and counting..._
 
 ---
 
@@ -407,6 +407,7 @@ _1535 TILs and counting..._
 - [Not So Random](go/not-so-random.md)
 - [Parse A String Into Individual Fields](go/parse-a-string-into-individual-fields.md)
 - [Parse Flags From CLI Arguments](go/parse-flags-from-cli-arguments.md)
+- [Redirect File To Stdin During Delve Debug](go/redirect-file-to-stdin-during-delve-debug.md)
 - [Replace The Current Process With An External Command](go/replace-the-current-process-with-an-external-command.md)
 - [Sleep For A Duration](go/sleep-for-a-duration.md)
 - [Sort Slice In Ascending Or Descending Order](go/sort-slice-in-ascending-or-descending-order.md)

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

@@ -0,0 +1,39 @@
+# 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
+```