What are the most commonly used modes when opening a file?

$($a$)$ppend$,($r$)$edline$,($w$)$rite

$($a$)$ppend$,($c$)$lose$,($w$)$rite

$($a$)$ppend$,($r$)$ead$,($w$)$rite

$($s$)$ave$,($r$)$ead$,($w$)$rite