2020-11_ Technical experience set

1. How to refresh local DNS cache ？

#  Administrator permission open cmd Command window 
ipconfig /flushdns

2. windons How to open it quickly hosts file ？

• Shortcut keys win+r Exhale “ function ” Program
• Enter... In the run box drivers, then “ determine ”
• In the pop-up folder , open etc Folder
• etc Visible in the folder HOSTS file , Right click “ open ”

3. vi Using skills

• edit
  Enter... On the command line vi +26 samp.txt The command directly opens the file to 26 That's ok , stay vi You can also enter
  :set number This command displays the line number on the left side of the editor .
• Fast navigation
  i Change the working mode from “ Command mode ” Change to “ The input mode ”, And start inserting content at the current cursor position .
  a Except that you start inserting content after the cursor , The effect is the same as above .
  o Start inserting content at the next line of the cursor .
• Delete
  x Delete the character of the current cursor .
  dd Delete current row （ Yes , The whole line ！)
  Let's look at the terrible part ：30dd Delete the following from the current line 30 That's ok ！ Please be careful when using this command .
• Search for
  Search for < > And move the cursor to the first match .
  Navigate to the next match of the word , Please enter n And continue to press , Until you find what you are looking for .
• Save and exit
  :x Save your work and exit Vi .
• Replace
  :%s/desktop/laptop/g This command will be in the whole file “desktop” use “laptop” Replace , He's like Linux Of sed command .

4. Linux command

#  Upload to ftp The server 
wget --ftp-user=<username> --ftp-password=<passwd> ftp://<server_ip>/<file_path>
#  decompression tar file 
tar -zxvf  <filename>.tar.gz

5. Kafka command

#  View all  topic  list 
./kafka-topics.sh --zookeeper {ip}:2181 --list

#  establish  topic  The theme 
./kafka-topics.sh --create --zookeeper {ip}:2181 --replication-factor 1 --partitions 1 --topic {topic_name}

#  Create producer messages 
./kafka-console-producer.sh --broker-list {ip}:9093 --topic {topic_name}

#  see  topic  news 
./kafka-console-consumer.sh --bootstrap-server {ip}:9093 --topic {topic_name} --from-beginning

#  eliminate  kafka  Group message 
./kafka-consumer-groups.sh --bootstrap-server {ip}:9093 --group {group_name} --topic {topic_name} --reset-offsets --to-earliest --execute

6. Kubectl command

#  view help 
kubectl --help
#  Look at the mirror image 
docker images |grep <sts_name>
#  Replace the image version number 
kubectl edit sts <sts_name>
#  Restart the service 
kubectl delete po <server_name>
 Into the container 
kubectl exec -it <containerName> bash
#  View the service real-time log 
kubectl logs <containerName> -f
#  Show  Pod  Details of ,  Especially view  pod  Log when cannot be created 
kubectl describe pod <pod-name>

7. Redis command

#  Select database 
select 1

FQA

1. Linux Command how to test api？

curl -H "Content-Type: application/json"  -X POST  -d '{ "pageNo": 1, "pageSize": 10 }'  "http://127.0.0.1:8080/test"

2. Warning FailedScheduling default-scheduler 0/1 nodes are available: 1 Insufficient cpu.

# (1)  View service information 
kubectl describe nodes
# (2)  Edit to stop other unused service copies , Free up resources 
kubectl edit sts <sts_name>
# (3)  Just restart the service 

3. How to see the type of server graphics card ？

nvidia  -smi

4. vi How to quickly replace words

dw  #  Intercept the next word 

5. redis How to get key Expiration time ？

TTL Command is used to get the remaining time of key expiration ( second ).
Return value
Integer value in milliseconds TTL Or negative value
TTL In Milliseconds .
-1, If key No expiration timeout .
-2, If the key doesn't exist .

ttl  key

6. git commit Modify the last submitted annotation information ?

 git commit --amend

7. git Merge multiple Commit?

A detailed reference

#  edit n Time submission record , open vi after , After the first pick Change it to s Save and exit , Pop up submission comments , Modify and save .

git rebase -i HEAD~n
#  Undo modify , Return to the state before the merge operation 
git rebase --abort