Created SC3029 (markdown)

SC3029.md

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+## In POSIX sh, `|&` in place of `2>&1 |` is undefined.
+
+### Problematic code:
+
+```sh
+#!/bin/sh
+make |& tee ~/log
+```
+
+### Correct code:
+
+Either switch to bash:
+
+```sh
+#!/bin/sh
+make 2>&1 | tee ~/log
+```
+
+### Rationale:
+
+Your script uses a shell feature not supported by the shebang. Either rewrite the script to be portable, or change the shebang to explicitly require a shell like Bash.
+
+In this case, the non-portable shorthand `|&` to pipe both stdout and stderr can be easily replaced with its written out form `2>&1 |` as shown.
+
+### Exceptions:
+
+None
+
+### Related resources:
+
+* Help by adding links to BashFAQ, StackOverflow, man pages, POSIX, etc!