Created SC3003 (markdown)

SC3003.md

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+## In POSIX sh, $'..' is undefined.
+
+### Problematic code:
+
+```sh
+#!/bin/sh
+IFS=$' \t\n'
+```
+
+### Correct code:
+
+```sh
+#!/bin/sh
+# Note: \n can not be last, or it will be stripped by $()
+IFS=$(printf ' \n\t')
+```
+
+or 
+
+```sh
+#!/bin/sh
+# Trailing linefeed added literally
+IFS="$(printf ' \t')
+"
+```
+
+or
+
+```sh
+#!/bin/bash
+# Bash supports this
+IFS=$' \t\n'
+```
+
+### Rationale:
+
+You are using the interpolated string Bashism `$'..'` in a script that declares itself as POSIX sh (e.g. via `#!/bin/sh`).
+
+To ensure the script runs correctly on other systems, either switch to Bash, or rewrite it in a POSIX compatible way.
+
+This can generally done via `printf` as in the example. Be careful about strings with trailing linefeeds, as a `$(command substitution)` will strip them.
+
+### Exceptions:
+
+None.
+
+### Related resources:
+
+* StackOverflow: [Why does my bash code fail when I run it with sh?](https://stackoverflow.com/questions/15179446/why-does-my-bash-code-fail-when-i-run-it-with-sh)