shell脚本案例学习

循环求 1-100 的每一步和 —案例

j=0
i=1
while((i<=100))
do
j=$((j+i))
echo $j
((i++))
done

每 30 s循环判断一次 user 用户是否登录系统 —案例
设置了一个次数，如果循环了五次在user文件中添加user用户，表示用户登录

USERS="user"
Times=0
while true; do
echo "$Times"
if [[ $Times == 5 ]]; then
 user >> user
 ((Times++))
fi
 echo "The Time is $(date +%F-%T)"
 sleep 30
 NUM=$(grep "$USERS" user| wc -l)
 if [[ $NUM == 1 ]]; then
   echo "The $USERS is login in system."
 fi
done

没+1，不知道什么原因

检查了以下，逻辑错了，++放在外面,同时重定向也写错了，没加echo

USERS="user"
Times=0
while true; do
echo "$Times"
((Times++))
if [[ $Times == 5 ]]; then
 echo user >> user
fi
 echo "The Time is $(date +%F-%T)"
 sleep 30
 NUM=$(grep "$USERS" user| wc -l)
 if [[ $NUM == 1 ]]; then
   echo "The $USERS is login in system."
 fi
done

这下ok了