Created SC3050 (markdown)

SC3050.md

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+## In POSIX sh, `printf %q` is undefined.
+
+(or "In dash, ... is not supported." when using `dash`)
+
+### Problematic code:
+
+```sh
+ssh host "cat $(printf "%q" "$remotefile")"
+```
+
+### Correct code:
+
+There is not really a good, built-in way to escape a string for a remote shell in POSIX sh. However, you can replace each `'` in the input with `'\''` and then wrap the whole results in single quotes:
+
+```sh
+escape() { printf "'%s'\\n" "$(printf '%s' "$1" | sed -e "s/'/'\\\\''/g")"; }
+ssh host "cat $(escape "$remotefile")"
+```
+
+Alternatively, switch to a shell that *does* support `printf %q` like `ksh` or `bash`.
+
+### Rationale:
+
+`printf %q` is a bash and ksh extension. It's not supported on POSIX sh or dash.
+
+### Exceptions:
+
+If the command is gated by a check for the correct shell, you can [[ignore]] this warning.
+
+### Related resources:
+
+* Help by adding links to BashFAQ, StackOverflow, man pages, POSIX, etc!