shell脚本实战-while循环语句

while [条件]
do
 操作
done

while read line
do
 操作
done < file

while true ;do
	echo 'helloword'
done

#!/bin/bash

num=1

while [ $num -le 10 ]
do
	echo $num
	num=$(( $num + 1 ))
done

while read line
do
	echo $line
done <./a.txt

cat ./a.txt|
while read line
do
	echo $line 
done

#!/bin/bash
content=$(cat ./a.txt)
for i in $content
do
 echo $i
done

#!/bin/bash
num=1
while [ $num -lt 10 ]
do
	sum=$(( $num * $num))
	echo "$num * $num = $num"
	((num++))
done

#!/bin/bash
num=1
while [ $num -lt 10 ]
do
	sum=$(( $num * $num))
	echo "$num * $num = $sum"
	((num++))
done

[root@ecs-c13b ~]# cat name.txt 
zhangsan
lisi
wangwu

#!/bin/bash
for name in `cat /root/name.txt`
#for name in $(cat /root/a.txt)
do
  id $name &> /dev/null
  if [ $? -ne 0 ];then
    useradd $name
    echo "123456" |passwd --stdin $name &> /dev/null
    echo "user $name created"

  else
    echo "user $name is exist"
  fi
done