Added proposed printf %q

SC2039.md

@@ -107,4 +107,40 @@ printf '%s' "$g" | grep aaa # since we want to avoid `echo`
 
 ### echo flags
 
-See koalaman/shellcheck#461.
+See https://unix.stackexchange.com/tags/echo.
+
+### `${var/pat/replacement}`
+
+Bash:
+
+```Bash
+echo "${TERM/%-256*}"
+```
+
+POSIX:
+
+```sh
+echo "$TERM" | sed -e 's/-256.*$//g'
+```
+
+### `printf %q`
+
+Bash:
+
+```Bash
+printf '%q ' "$@"
+```
+
+POSIX:
+
+```sh
+# TODO: possibly interpret it back to printf escapes for hard-to-copy chars like \t
+reuse_quote()(
+  for i; do echo -n \'; echo -n "$i" | sed -e "s/'/'\\\\''/g"; echo -n "' "; done
+)
+reuse_quote "$@"
+```
+
+## Exception
+
+Depends on what your expected POSIX shell providers would use.