碰巧看到你给别人解答的Linux不过还没看懂,/bin/bashuntilwho|grep"$1">/dev/nulldosleep60done#nowringthebellandannouncetheexpecteduserecho-e'\a'echo"能从第一行开始解释一下每一行的意思吗,这个结果

Question

碰巧看到你给别人解答的Linux 不过还没看懂,
/bin/bash
until who | grep "$1" > /dev/null
do
sleep 60
done
#now ring the bell and announce the expected user
echo -e '\a'
echo "
能从第一行开始解释一下每一行的意思吗,这个结果是怎么造成的?

Answer 1

until who | grep "$1" > /dev/null
do
sleep 60
done
每隔一分钟查看一次有没有人登陆
echo -e '\a'
echo "*****$1 has just logged in ****"
如果有人登陆,那么响铃一声,并提示是谁登陆了