Created SC2332 (markdown)

SC2332.md

@@ -0,0 +1,47 @@
+##  [ ! -o opt ] is always true because -o becomes logical OR. Use [[ ]] or ! [ -o opt ].
+
+Or "`[ ! -a file ]` is always true because `-a` becomes logical AND. Use `-e` instead."
+
+
+### Problematic code:
+
+```sh
+if [ ! -o braceexpand ]
+then 
+  ..
+fi
+```
+
+### Correct code:
+
+```sh
+if [[ ! -o braceexpand ]]
+then 
+  ..
+fi
+```
+
+or 
+
+```sh
+if ! [ -o braceexpand ]
+then 
+  ..
+fi
+```
+
+### Rationale:
+
+Bash interprets `[ ! -o opt ]` as `[ "!" ] || [ "opt" ]` instead of negating the condition. As a result, the condition is always true.
+
+Avoid this by using `[[ ! -o opt ]]` or `! [ -o opt ]`.
+
+The same issue applies to `[ ! -a file ]`, but this is easier fixed using POSIX standard `[ ! -e file ]`.
+
+### Exceptions:
+
+None.
+
+### Related resources:
+
+* Help by adding links to BashFAQ, StackOverflow, man pages, POSIX, etc!