Bash: loops

for i in $( ls ) do echo $i done 

for i in $( seq 1 10 ) do echo $i done 

for ((i = 0 ; i < max ; i++ )) do echo $i done 

i=0 while [ $i -lt 10 ] do echo $i i=$((i+1)) done 

i=20 until [ $i -lt 10 ] do echo $i i=$((i-1)) done