SHELL训练营--day20_shell练习41-45

#问候脚本
#!/bin/bash
d=`date +%H`
if [ $d -ge 0 -a $d -lt 7 ]
then
tag=1
elif [ $d -ge 7 -a $d -lt 12 ]
then
tag=2
elif [ $d -ge 12 -a $d -lt 18 ]
then
tag=3
else
tag=4
fi

case $tag in
1)
echo "早上好"
;;
2)
echo "上午好"
;;
3)
echo "下午好"
;;
4)
echo "晚上好"
;;
esac

#菜单脚本
#!/bin/bash
echo -e "1) w\n2) ls\n3) pwd\n4) quit"
while
do
read -p "Please input your choice(1-4):" c
case $c in
1)
w
;;
2)
ls
;;
3)
pwd
;;
4)
exit
;;
*)
echo "Please input 1-4."
;;
esac
done

#检查用户登录
#!/bin/bash
while :
do
if w|sed '1'd|awk '{print $1}'|grep -qw "$1"
then
echo "$1 用户已经登录。"
fi
sleep 300
done

#检查系统是否被***
#!/bin/bash
pp=$$
ps -elf|sed '1'd > /tmp/pid.txt
for pid in `awk -v ppn=$pp '$5!=ppn {print $4}' /tmp/pid.txt`
do
if ! [ -d /proc/$pid ]
then
echo "系统中没有pid为$pid的目录。请检查。"
fi
done

#三行合一行
#!/bin/bash
n=1
cat $1|while read line
do
n1=$[$n%3]
if [ $n1 -eq 0 ]
then
echo "$line"
else
echo -n "$line "
fi
n=$[$n+1]
done