Created SC2328 (markdown)

SC2328.md

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+## This redirection takes output away from the command substitution.
+
+(and companion warning "This command substitution will be empty because the command's output gets redirected away" which points to the relevant command substitution)
+
+### Problematic code:
+
+```sh
+var=$(tr -d ':' < input.txt > output.txt)
+```
+
+### Correct code:
+
+```sh
+# If the output should be captured INSTEAD OF being written to file
+var=$(tr -d ':' < input.txt)
+
+# If the output should be captured IN ADDITION to being written to file
+var=$(tr -d ':' < input.txt | tee output.txt)
+
+# If the output should NOT BE captured at all
+tr -d ':' < input.txt > output.txt
+```
+
+### Rationale:
+
+ShellCheck has found a command substitution (`$(..)`, `` `..` ``) that appears to never capture any output because the command's output is being redirected.
+
+Decide whether you want the output to be captured (by removing the redirection), to go into wherever it's redirected (by not running the command in a command substitution), or both (by using `tee` to copy the output to both file and stdout).
+
+### Exceptions:
+
+None
+
+### Related resources:
+
+* Help by adding links to BashFAQ, StackOverflow, man pages, POSIX, etc!