Created SC2180 (markdown)

SC2180.md

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+## Bash does not support multidimensional arrays. Use 1D or associative arrays.
+
+### Problematic code:
+
+```sh
+foo[1][2]=bar
+echo "${foo[1][2]}"
+```
+
+### Correct code:
+
+In bash4, consider using associative arrays:
+```sh
+declare -A foo
+foo[1,2]=bar
+echo "${foo[1,2]}"
+```
+
+Otherwise, do your own index arithmetic:
+```sh
+size=10
+foo[1*size+2]=bar
+echo "${foo[1*size+2]}"
+```
+
+### Rationale:
+
+Bash does not support multidimensional arrays. Rewrite it to use 1D arrays. Associative arrays map arbitrary strings to values, and are therefore useful since you can construct keys like `"1,2,3"` or `"val1;val2;val3"` to index them.
+
+### Exceptions:
+
+None.