1, briefly describes the TCP three handshake four times the wave process and the client and server state in each process.
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#三次握手
客户端向服务器端发送SYN包,客户端进入SYN_SEND状态
服务器端收到客户端发送的包返回ACK+SYN包,服务器端进入SYN_RECV状态
客户端收到服务器端返回的包再发回ACK包,客户端进入ESTABLISHED状态,服务器端收到包也进入ESTABLISHED状态
客户端状态:SYN_SENDE STABLISHED
服务器端状态:SYN_RCVE ESTABLISHED
#四次挥手
客户端发送FIN包询问服务器端是否能断开,客户端进入FIN_WAIT_1状态
服务器端收到客户端发送的包并返回ACK包,服务器端进入CLOSE_WAIT状态
服务器端准备好断开后,发送FIN包给客户端,服务器端进入LAST_ACK状态
客户端收到服务器端发送的包后返回ACK包,客户端进入TIME_WAIT状态,服务器端收到包后进入CLOSED状态
客户端状态:FIN_WAIT_1 FIN_WAIT_2 TIME_WAIT
服务器端状态:CLOSE_WAIT LAST_ACKC LOSED
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2, talk about the difference between the process and the thread
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进程是并发执行的程序在执行过程中分配和管理资源的基本单位。 线程是进程的一部分,线程的改变只代表了 CPU 执行过程的改变,而没有发生进程所拥有的资源变化。 |
3. Query file.txt the line ending with ABC
4. Delete blank lines in the File.txt file
5. Print the 10th line in the File.txt file
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sed -n ‘10p‘ file .txt head -10 file .txt | tail -1 |
6. Backup and restore MySQL database test
Backup:
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mysqldump -uroot -pPassword -hHostname test > /root/test .sql |
Recovery:
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mysql -uroot -pPassword -hHostname < /root/test .sql |
7. Use Netstat to count the number of connections to the various states of the current TCP connection.
1 |
netstat -nat| awk ‘{print $6}‘ | sort | uniq -c |
8, Linux under How to convert GBK encoded format test_gbk.txt file into UTF-8 encoding format, the converted file name is Test_utf8.txt
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iconv -f GBK -t UTF-8 test_gbk.txt -o test_utf8.txt |
9. Say what monitoring software you have used, and briefly describe its principles and application scenarios
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#zabbix agent方式监控:在被监控端安装agent程序,通过zabbix自己的协议主动或被动发送数据给server端或代理的proxy端, 适用于服务器、工作站的监控,不适用于交换机、路由器、防火墙的监控。 SNMP方式监控:通过SNMP协议进行监控,需要开起并配置SNMP服务,适用于网络设备(交换机、路由器、防火墙)的监控, 通信协议为UDP,所以不适用于服务器、工作站的监控。 |
10. Write commands to view Linux system performance, such as CPU, memory, traffic, IO, etc.
Top,free,iftop,iostat
11, said Nginx upstream support allocation strategy, and briefly describe its principle
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轮询:默认的方式,按时间顺序依次分配 weight:根据服务器权重进行轮询分配 ip_hash:按ip的 hash 值进行分配,可以解决session保持 url_hash:按访问url的 hash 结果来分配请求,使每个url定向到同一个后端服务器,后端服务器为缓存时比较有效 fair:按服务器响应时长进行分配 |
12, crontab timing: In November, every day in the morning 6 to 12 points, every 2 hours to perform a/usr/bin/httpd.sh how to achieve
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0 6-12 /2 * 11 * /usr/bin/httpd .sh |
13, iptables prohibit IP 10.10.10.1 access to local 80 port
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iptables -t filter -I INPUT -p tcp -s 10.10.10.1 --dport 80 -j DROP |
14. Find the content in file a but not in file B, and write the script after the command
12 |
#!/bin/bash diff /root/a /root/b | grep "<" | awk ‘$1=" "‘ |
15. Write a shell loop to create 100 users, user name format user_[0~99]
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#!/bin/bash for i in {1..100}; do useradd user_$i done echo "ok" |
Linux Basics Quiz