shell 循环

简单循环 （for）

for i in {1..100}
do
	echo "$i"
done

# 范围支持
	## 空格 1 2 3 4
	## tab  1	2	3
	##  for i in (cat  file.txt)
	##  for i in seq 100   			# 1到一百
	##  for i in seq 2 100   		# 2到一百
		##  for i in $(seq -w 2 100)   # 0 填充
-------------------------------------------------------------------------------

 for i in {a..z}
do
	echo "$i"
done
-------------------------------------------------------------------------------
# 两个集合破解
 for i in {a..z}{1..10}
do
	echo "$i"
done
-------------------------------------------------------------------------------
# 上上边的区别在于  这个次数是一个变量
i={次数}
for ((j=0; j<i; j++)); do
	执行多少次
done

双重循环

for i in {1..100}
do
    # clear
    line="<---------------------------------------------------------------------------------------------------->"
    for ((j=0; j<i; j++)); do
        line=$(echo "$line" | sed 's/-/=/')
    done
    echo "$line $i %"
    sleep 0.1
    # echo "$i"
    # echo "Hello, World!"
    
done

循环(while)

i=0
while [$i -lt 100]
do 
	a=$[$a+1]
	echo "$a"
done

let a++

i=0
while [$i -lt 100]
do 
	let a++
	echo "$a"
done

跳过循环(continue、break)

 for i in {1..10}
do
	if [ $i eq 5 ];then
		continue
	fi
	echo "$i"
done
# continue 跳过本次循环
# break 结束整个循环
# exit 结束程序

---

循环案例

99乘法表

for i in $(seq 9)
do
    for j in $(seq 9)
    do
        echo -ne "$i * $j = $(($i * $j))\t"
    done
    echo ''
done

echo -----------------------------------------------------------------------
# 三角

for i in $(seq 9)
do
    
    for j in $(seq $i)
    do
        echo -ne "$i * $j = $(($i * $j))\t"
    done
    echo ''
done

创建十个用户

# 创建十个用户 截取uuid 第一段为 密码  把密码保存到一个文件中
# user_01  -- user_10
uname=user_
isPasswd="密码是"
for i in $(seq -w 10)
do
    echo $uname$i
    useradd $uname$i 
    
    myPasswd=$(echo `uuidgen` | awk -F "-" '{print $1}')
    echo $myPasswd | passwd  --stdin $uname$i

    echo $uname$i$isPasswd$myPasswd >> ./myP.txt
	# userdel -r $uname$i  # 删除用户
done

---

坚持 是一个很简单的事情 也是一个很困难的事情