Linux Basics Quiz

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

2, talk about the difference between the process and the thread

12	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

1	grep"abc$"file.txt

4. Delete blank lines in the File.txt file

1	sed-i ‘/^$/d‘file.txt

5. Print the 10th line in the File.txt file

123	sed-n ‘10p‘ file.txt head -10 file.txt | tail-1

6. Backup and restore MySQL database test

Backup:

1	mysqldump -uroot -pPassword -hHostname test>/root/test.sql

Recovery:

1	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

1	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

1	0 6-12/2* 11 * /usr/bin/httpd.sh

13, iptables prohibit IP 10.10.10.1 access to local 80 port

1	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/bashdiff/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/bashfori in {1..100};do        useradd user_$idoneecho"ok"

Linux Basics Quiz