Created SC2239 (markdown)

SC2239.md

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+## Ensure the shebang uses the absolute path to the interpreter.
+
+### Problematic code:
+
+```sh
+#!bin/sh
+echo "Hello World"
+```
+
+### Correct code:
+
+```sh
+#!/bin/sh
+echo "Hello World"
+```
+
+### Rationale:
+
+The script's interpreter, as specified in the shebang, does not start with a `/`.
+
+The interpreter should always be specified by absolute path to ensure that the script can be executed from any directory. When it's not, it's generally a typo like in the problematic example.
+
+If you don't know where the interpreter is and you hoped to use `#! bash`, this is not an option. Use `/usr/bin/env` instead:
+
+```sh
+#!/usr/bin/env bash
+echo "Hello World"
+``` 
+
+While not required by POSIX, `env` can essentially always be found in `/usr/bin` and will search the PATH for the specified executable.
+
+### Exceptions:
+
+None.
+
+### Related resources:
+
+* Help by adding links to BashFAQ, StackOverflow, man pages, POSIX, etc!