1、shell的计算

#!/usr/bin/env bash##计算##result=`expr 2 - 100`echo "$result"result1=$((5+5))echo "$result1"result2=$[5+4]echo $result2let result3=2+4echo $result32、for循环举例

for var in 1 2 3 4 5 6 7 8 9 do echo "then is number is $var" donefor var1 in {10..19} do echo "then is number is $var1" donefor var2 in `seq 20 28` do echo "then is numver is $var2" done