if语句和for语句

#!/bin/bash

i=4
if [ $i -lt 5 ];then
	echo "22222222222";
fi

a=3
if [ $a -ne 1 -a $a != 2 ];then
	echo "33333333333";
fi

if [ $a -ne 1 ] && [ $a != 2 ];then
	echo "444444444444";
fi

if [[ $a != 1 && $a != 2 ]];then
	echo "5555555555";
fi

b2=2
c3=3
if [ $b2 -gt $c3 ];then
	echo "$b2 > $c3"
else
	echo "$c3 > $b2"
fi

if [ $b2 -gt $c3 ];then
	echo "$b2 > $c3"
elif [ $b2 -eq $c3 ];then
	echo "$b2 = $c3"
else
	echo "$b2 < $c3"
fi


for i in $(seq 0 4);do
	echo $i;
done

for i in `seq 0 4`;do
	echo $i;
done

for ((i=0;i<5;i++));do
	echo $i;
done

for i in {0..4};do
	echo $i;
done