| true; ``; echo $? | |
| false; ``; echo $? | |
| true; `""`; echo $? | |
| false; `""`; echo $? | |
| true; ` `; echo $? | |
| false; ` `; echo $? | |
| true; $(); echo $? | |
| false; $(); echo $? | |
| true; $(""); echo $? | |
| false; $(""); echo $? | |
| true; $( ); echo $? | |
| false; $( ); echo $? | |
| true; exec ''; echo $? | |
| false; exec ''; echo $? |