Shell 流程控制if,case,for,while

if

if [ 条件判断 ] #第二种，推荐使用
then
     #content
elif [ 条件判断 ] #else无需[ 条件判断 ],也不需要then
then
     #content
fi

case

#!/bin/bash
case $1 in
"1")
echo "Monday"
;;
"2")
echo "Tuesday"
;;
*) #缺省值
echo "ha?"
;;
esac 

for

#命令 ./myShell.sh 10 20
#!/bin/bash
for i in "$*"
do
      echo "nums are $j" #输出10 20
done

for j in "$@"
do
      echo "num is $i" #分行输出num is 10, num is 20
done

#!/bin/bash
SUM=0
for ((i=1;i<=100;i++))
do
    SUM=$[$SUM+$i] 
done
echo "SUM=$SUM"

while

#!/bin/bash
COUNT=0
SUM=0
while [ $COUNT -lt $1 ]
do
      COUNT=$[$COUNT+1]
      SUM=$[$COUNT+$SUM]
done
echo "SUM=$SUM"