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+## In POSIX sh, arithmetic for loops are undefined.
+
+### Problematic code:
+
+```sh
+for ((i=0; i<10; i++))
+do 
+  echo "$i"
+done
+```
+
+### Correct code:
+
+```sh
+i=0
+while [ "$i" -lt 10 ]
+do 
+  echo "$i"
+  : $(( i += 1 ))
+done
+```
+
+### Rationale:
+
+C-style arithmetic for loops are a Ksh/Bash feature that's not supported by POSIX sh or dash. Use a `while` loop with separate initialization and incrementing instead.
+
+### Exceptions:
+
+None
+
+### Related resources:
+
+* Help by adding links to BashFAQ, StackOverflow, man pages, POSIX, etc!
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