Summary of daily O & M work knowledge

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1. vmtools is automatically installed on Windows virtual machines.

• Connect to esxi through a client: client-install vmtools
• Go to the system and run cmd./ke:&&setup /s/v/qn(E: drive letter)

2. End user sessions

• View who is logging on to the system: W
• In Linux, run pkill-9-t pts to kill other commands that are logging on to the user through SSH./3

3. view the TCP connection status and number

• netstat -n|awk‘/^tcp/ {++S[$NF]}END {for(a in S) print a,S[a]}‘
• /usr/sbin/ss -n|awk‘{++S[$1]} END {for(a in S) print S[a],"\t",a}‘

4. Analyze access. log to obtain the top 10 IP addresses

• awk ‘{print $1}‘ access.log |sort|uniq -c|sort -nr|head -10

5. Real-time traffic monitoring

• yum -y install nload
• For detailed command usage, see: https://linux.cn/article-2871-1.html

6. Prevent rsyslog loss caused by too much log output

• echo"$SystemLogRateLimitInterval 60" >> /etc/rsyslog.conf
• echo"$SystemLogRateLimitBurst 3000" >> /etc/rsyslog.conf

7. Delete massive directory commands:

• find ./ -type f | xargs -I {} rm -F {} (enter the directory to be deleted)
• rsync --delete-before -a -H -v --progress --stats /tmp/ ./(Replace the directory to be deleted with an empty directory)

8. Route Tracking command:

• mtr 10.10.10.1

9. Ssh disconnection solution:

• ClientAliveInterval 120
• ClientAliveCountMax 3

10. Zero-time download is provided: (listen to 8888 on 10.10.10.10 )??

• nc -l 8888 < /root/drbd-8.4.1.tar.gz
• Download the client:wget http://10.10.10.10:8888/drbd-8.4.1.tar.gz

11. lftp download instance:

• lftp -c "pget -n 10 -O ./ ftp://test:[email protected]:21/kisops_centos6.3_vm_4G.iso"

12. lftp upload instance:

• lftp -c put /data/apps/kisops_centos6.3_vm_4G.iso -o ftp://test:[email protected]:2/kisops_centos6.3_vm_4G.iso

13. SMB client mounting command:

• mount -t cifs -o async,soft,rw,username=ftp,password=123456 //172.28.29.249/Share /sandata/data

14. Run a script on a remote machine. The biggest benefit of this command is that you do not need to copy the script to a remote machine:

• ssh [email protected] bash < /path/to/local/script.sh

15. Test the read/write speed of the hard disk:

• Write:time dd if=/dev/zero of=/usr/mfstest/test2/zhhtest500Mbs=1024k count=500
• Read:time dd if=/usr/mfstest/test2/zhhtest500Mof=/dev/null

16. view the system Sn:

• dmidecode | grep "Serial Number“

17. Fixed an error caused by the format of the script copied to Linux:

• yum install dos2unix
• Dos2unix cactirelease. Sh (problematic script format)

18. centos6 series emails with attachments:

• Echo "this is a test mail" | mail-s "test"-A/etc/passwd [email protected] (Mail title: Test, mail body: this is a test mail, attachment: passwd file under/etc/

19. Ping prohibited in Linux:

• echo 1 > /proc/sys/net/ipv4/icmp_echo_ignore_all

2018.write 10.10.1-254to iplist.txt, one line in two ways:

• printf ‘%s\n‘ 10.10.10.{1..254} >iplist.txt
• echo 10.10.10.{1..249} | tr ‘ ‘ ‘\n‘ >> iplist.txt

21. Check whether the machine has several CPUs:

• cat /proc/cpuinfo | grep physical | uniq -c
• Lscpu

22. Add the default route:

• windows:　　route -p add 0.0.0.0 mask 0.0.0.0 162.28.29.32
• linux：　　route add -net 0.0.0.0 netmask 0.0.0.0 gw 162.28.29.32

23. view the sn of the vswitch model:

• display device manuinfo

24. Delete 0-byte files:

• find -type f -size 0 -exec rm -rf {} \;

25. Obtain the IP Address:

• ifconfig eth0 |grep "inet addr:" |awk ‘{print $2}‘|cut -c 6-
• Or
• ifconfig | grep ‘inet addr:‘| grep -v ‘127.0.0.1‘ | cut -d: -f2 | awk ‘{ print $1}‘

26. Kill the process related to port 80:

• lsof -i :80|grep -v "ID"|awk ‘{print "kill -9",$2}‘|sh

27. Clear dead processes:

• ps -eal | awk ‘{ if ($2 == "Z") {print $4}}‘ | kill -9

28. View File filtering # Start With and blank lines

• cat lvs.cfg | grep -v "#" | awk ‘NF‘

Summary of daily O & M work knowledge