1.显示统计占用系统内存最多的进程，并排序.
[root@localhost ~]#ps aux --sort -rss |head -5
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
root 6311 0.0 0.6 573816 14024 ? Ssl Sep16 3:16 /usr/bin/python2 -Es /usr/sbin/tuned -l -P
root 6314 0.0 0.4 298268 8856 ? Ssl Sep16 1:40 /usr/sbin/rsyslogd -n
root 6057 0.0 0.3 699056 7972 ? Ssl Sep16 0:46 /usr/sbin/NetworkManager --no-daemon
root 3016 0.0 0.3 39080 7776 ? Ss Sep16 2:03 /usr/lib/systemd/systemd-journald
[root@localhost ~]#ps aux --sort -%mem |head -5
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
root 6311 0.0 0.6 573816 14024 ? Ssl Sep16 3:16 /usr/bin/python2 -Es /usr/sbin/tuned -l -P
root 6314 0.0 0.4 298268 8856 ? Ssl Sep16 1:40 /usr/sbin/rsyslogd -n
root 6057 0.0 0.3 699056 7972 ? Ssl Sep16 0:46 /usr/sbin/NetworkManager --no-daemon
root 3016 0.0 0.3 39080 7776 ? Ss Sep16 2:03 /usr/lib/systemd/systemd-journald
2.编写脚本，使用for和while分别实现192.168.0.0/24网段内，地址是否能够ping通，若ping通则输出"success!"，若ping不通则输出"fail!".
for循环
[root@localhost /data/scripts]#bash !*
bash ip_for.sh
192.168.11.1 is success!
192.168.11.3 is success!
192.168.11.8 is success!
192.168.11.9 is success!
192.168.11.5 is success!
192.168.11.34 is success!
192.168.11.15 is success!
192.168.11.47 is success!
192.168.11.31 is success!
192.168.11.32 is success!
192.168.11.6 is success!
192.168.11.33 is success!
192.168.11.46 is success!
192.168.11.10 is success!
192.168.11.45 is success!
192.168.11.142 is success!
192.168.11.11 is fail!
[root@localhost /data/scripts]#cat !*
cat ip_for.sh
#!/bin/bash
#********************************************************************
#Author: Kevin.Wen
#Revision: 1.0
#QQ: 2510905014
#Date： 2020-10-16
#FileName： ip_for.sh
#********************************************************************
NETID=192.168.11.
for HOSTID in {1..254};do
{
if /bin/ping -c1 -W1 $NETID$HOSTID >/dev/null ; then
echo "$NETID$HOSTID is success!"
else
echo "$NETID$HOSTID is fail!"
fi
} &
done
wait
while循环
[root@localhost /data/scripts]#bash ip_while.sh
192.168.11.3 success!
192.168.11.1 success!
192.168.11.6 success!
192.168.11.5 success!
192.168.11.15 success!
192.168.11.9 success!
192.168.11.8 success!
192.168.11.46 success!
192.168.11.32 success!
192.168.11.31 success!
192.168.11.34 success!
192.168.11.47 success!
192.168.11.10 success!
192.168.11.45 success!
[root@localhost /data/scripts]#cat ip_while.sh
#!/bin/bash
#********************************************************************
#Author: Kevin.Wen
#Revision: 1.0
#QQ: 2510905014
#Date： 2020-10-16
#FileName： ip_while.sh
#********************************************************************
NETID=192.168.11.
declare -i HOSTID=1
while [ $HOSTID -lt 254 ];do
{
ping -c1 -W1 $NETID$HOSTID &>/dev/null
if [ $? -eq 0 ];then
echo "$NETID$HOSTID success!"
else
echo "$NETID$HOSTID fail!"
fi
}&
let HOSTID++
done
wait
3.每周的工作日1:30，将/etc备份至/backup目录中，保存的文件名称格式 为“etcbak-yyyy-mm-dd-HH.tar.xz”，其中日期是前一天的时间.
[root@localhost /data/scripts]#cat etc_backup.sh
#!/bin/bash
#********************************************************************
#Author: Kevin.Wen
#Revision: 1.0
#QQ: 2510905014
#Date： 2020-10-16
#FileName： etc_backup.sh
#********************************************************************
[ -d /backup ] || mkdir /backup
rpm -q xz >/dev/null
[ $? -eq 0 ] || yum -y install xz >/dev/null
DATEFORMAT=`date -d yesterday "+%Y-%m-%d-%H"`
tar -Jcf /backup/etcbak-$DATEFORMAT.tar.xz /etc &> /dev/null
[root@localhost /data/scripts]#vim /etc/crontab
SHELL=/bin/bash
PATH=/sbin:/bin:/usr/sbin:/usr/bin
MAILTO=root
# For details see man 4 crontabs
# Example of job definition:
# .---------------- minute (0 - 59)
# | .------------- hour (0 - 23)
# | | .---------- day of month (1 - 31)
# | | | .------- month (1 - 12) OR jan,feb,mar,apr ...
# | | | | .---- day of week (0 - 6) (Sunday=0 or 7) OR sun,mon,tue,wed,thu,fri,sat
# | | | | |
# * * * * * user-name command to be executed
30 1 * * 0 root sh /data/scripts/etc_backup.sh &>/dev/null
4.工作日时间，每10分钟执行一次磁盘空间检查，一旦发现任何分区利用率高于80%，就发送邮件报警.
[root@localhost /data/scripts]#bash check_disk.sh
100
Warning!!!
/dev/sr0‘s avaliable space is less than 20%|mail -s Warning root
[root@localhost /data/scripts]#df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda2 100G 1.7G 99G 2% /
devtmpfs 980M 0 980M 0% /dev
tmpfs 991M 0 991M 0% /dev/shm
tmpfs 991M 72M 919M 8% /run
tmpfs 991M 0 991M 0% /sys/fs/cgroup
/dev/sda3 50G 169M 50G 1% /data
/dev/sda1 1014M 127M 888M 13% /boot
/dev/sr0 4.3G 4.3G 0 100% /mnt/cdrom
tmpfs 199M 0 199M 0% /run/user/0
[root@localhost /data/scripts]#cat check_disk.sh
#!/bin/bash
#********************************************************************
#Author: Kevin.Wen
#Revision: 1.0
#QQ: 2510905014
#Date： 2020-10-16
#FileName： check_disk.sh
#********************************************************************
Usage_Rate=`df |awk -F ‘[ %]+‘ ‘BEGIN{max = 0}{if ($5+0 > max) max=$5} END {print max}‘`
Partition_Name=`df |grep "$Usage_Rate%" |cut -d" " -f1`
echo $Usage_Rate
if [ $Usage_Rate -gt 80 ];then
echo -e "Warning!!! \n $Partition_Name‘s avaliable space is less than 20%|mail -s Warning root"
fi
*/10 * * * 1-5 root sh /data/scripts/check_disk.sh &>/dev/null