等于--->(eq)--->(equal)
if [ "$a" -eq "$b" ] 不等于--->(ne)--->(not equal)
if [ "$a" -ne "$b" ] 大于--->(gt)--->(greater than)
if [ "$a" -gt "$b" ] 大于等于--->(ge)--->(greater than or equal)
if [ "$a" -ge "$b" ]小于--->(lt)--->(less than)
if [ "$a" -lt "$b" ] 小于等于--->(le)--->(less than or equal)
if [ "$a" -le "$b" ] 
