Created SC2335 (markdown)

SC2335.md

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+## Use `[ "$var" -ne 1 ]` instead of `[ ! "$var" -eq 1 ]`
+
+and other binary operators such as
+
+- `=` and `!=` (string)
+- `-le` and `-gt`, and so forth (arithmetic)
+
+### Problematic code:
+
+```sh
+if [ ! "$var" -eq 1 ]; then :; fi
+if ! [ "$var" = foo ]; then :; fi
+```
+
+### Correct code:
+
+```sh
+if [ "$var" -ne 1 ]; then :; fi
+if [ "$var" != foo ]; then :; fi
+```
+
+### Rationale:
+
+Double negation of such binary oprators is unnecessary.
+
+### Exceptions:
+
+This is a stylistic issue that does not affect correctness. If you prefer the original expression, you can [[Ignore]] it with a directive or flag.
+
+This rule is not applied to the followings:
+
+- `<` and `>` (lexicographical)
+- `-nt` and `-ot` (file timestamp)
+- `=~` (regular expression)
+
+### Related resources:
+
+* Help by adding links to BashFAQ, StackOverflow, man pages, POSIX, etc!
+* [[SC2236]] and [[SC2237]] for unary operators `-n` and `-z`