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doc/bash_tips.md

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+# Bash Tips
+
+## prevent last false
+
+function body should not end up with a ternary statement
+
+### wrong last
+
+Compound of 2 'false' statement returns false.
+
+```bash
+[[ : ]] && [[ : ]]
+```
+
+### right last
+
+```bash
+[[ : ]] && [[ : ]] || true
+```
+
+## arithmetic issue
+
+last (++) statement does not complete successfully!
+
+### wrong ++
+
+```bash
+count=0
+(( ++count )) # ok 
+(( ++count )) # last statement in function returns false
+```
+
+### right ++
+
+```bash
+count=0
+count=$((count+1))
+`