Realize the scheduled backup of MySQL database in Linux environment through simple script (mysqldump command backup)

1、mysqldump command

  mysqldump yes mysql Utility for transferring storage databases . It mainly produces a SQL Script , It contains the commands necessary to recreate the database from scratch CREATE TABLE INSERT etc. .

 command ：mysqldump -h The host address  -u user name  -p Database password   Database name   surface 1  surface 2 >  file name 

   If the user name requires a password , You need to enter a password check after this command is executed ; If the database user name does not require a password , Do not add “-p” Parameters , The import time is the same . Note that the entered user name needs to have the operation permission of the corresponding database , Otherwise, data cannot be exported . Because it is for system maintenance and export of all databases , Generally we use root And other super user permissions .

Other command references

 Backup remote MySQL Database commands 
mysqldump -hhostname -uusername -ppassword databasename > backupfile.sql
 
 Backup MySQL The database is backed up in the form of deleted tables MySQL The database is in the form of deleted tables , The backup can overwrite the existing database without manually deleting the original database .
mysqldump ---add-drop-table -uusername -ppassword databasename > backupfile.sql
 
 Direct will MySQL Database compression backup 
mysqldump -hhostname -uusername -ppassword databasename | gzip > backupfile.sql.gz
 
 Backup MySQL A database ( some ) surface 
mysqldump -hhostname -uusername -ppassword databasename specific_table1 specific_table2 > backupfile.sql
 
 Backup multiple files at the same time MySQL database 
mysqldump -hhostname -uusername -ppassword --databases databasename1 databasename2 databasename3 > multibackupfile.sql
 
 Just back up the database structure 
mysqldump --no-data --databases databasename1 databasename2 databasename3 > structurebackupfile.sql
 
 Back up all databases on the server 
mysqldump --all-databases allbackupfile.sql
 
 Restore MySQL Database commands 
mysql -hhostname -uusername -ppassword databasename < backupfile.sql
 
 Restore compressed MySQL database 
gunzip < backupfile.sql.gz | mysql -uusername -ppassword databasename

2、crontab command

  crontab Commands are used to set the instructions that are executed periodically , And store it in /etc/crontab file , For later reading and execution .cron The system schedules the process , You can use it to run jobs during off peak load periods every day , Or run at different times of the week or month ,cron It is the main scheduling process of the system , Jobs can be run without human intervention .

Please refer to the details 《Linux Crontab Timing task 》

crontab Use

crontab [-u username]　　　　// Omitting the user table indicates the operation of the current user crontab
    -e      ( Edit the sheet )
    -l      ( List the orders in the worksheet )
    -r      ( Delete the work )

We use it crontab -e Enter the current user's worksheet edit , Is common vim Interface . Each line is a command .

crontab The order of is Time + action , The time is divided 、 when 、 Japan 、 month 、 On Friday , Operators have

Example ：

[[email protected] soft]# crontab -l
0 2 * * * bash /usr/soft/mysql_backup.sh? # Every morning 2 Click to execute once 
*/1 * * * * bash /usr/soft/mysql_backup.sh? #  Execute every minute 

3、 practice

   Through the previous understanding , We basically know mysql Export command mysqldump and Linux Timing command crontab The use of , Now let's try to realize the command of regularly backing up the specified tables in the specified database .

1、 Backup scripts

   First , establish mysql_backup.sh file , Define the script for backing up the database , The implementation is as follows ：

#!/bin/bash
  
# Backup location 
backup_dir='/usr/data/backup/mysql/'
# Get the current time 
current_time=$(date +'%Y-%m-%d_%H%M%S')
# take backup_dir Combined with time , Add a suffix 
filepath=$backup_dir$current_time'.sql.gz'

# database information , Configure database account password 
s_ip='127.0.0.1'
username='root'
password='xxx'
source_database='xxx'

echo "-----------------------"$(date +%F%r)" Operation start --------------------------------"
echo $(date +%F%r)" Start data backup ..."
# 2>/dev/null  Can suppress warning messages 
mysqldump -h${
    s_ip} -P3306 -u ${
    username} -p"${password}"  ${
    source_database} table1 table2 table3 | gzip > $filepath

echo $(date +%F%r)" Complete synchronization ..."

   The above script implements , Backup s_ip Host computer source_database database , And only backup table1、table2、table3 Three data sheets , And gzip Format compression , The storage path is backup_dir.

2、 exception handling

Be careful : appear “/bin/bash^M: bad interpreter: No such file or directory” Report errors
   Because in general , The script will be in windows Write... In the environment , This is the time , Secondary upload to Linux System time , There may be “/bin/bash^M: bad interpreter: No such file or directory” error , This is because shell The script file is dos Format , That is, each line ends with \r\n To mark , and unix Format file line ends with \n To mark . terms of settlement ：

1. Look at the format of the script : cat -A filename
   Judging from the display results ,dos Format file line ends with ^M$,unix Format file line ends with $.
2. Change the format of the script ：
   vi filename Open file , perform : set ff=unix Set the file to unix, And then execute :wq, Save as unix Format .
3. Look at the format of the script : cat -A filename
   Judging from the display results ,dos Format file line ends with ^M$,unix Format file line ends with $.

The execution script appears ：“-bash: ./mysql_backup.sh: Permission denied” abnormal
   This error is reported , The script is not authorized , The order is as follows ：

chmod u+x mysql_backup.sh 

The execution script appears ：“./mysql_backup.sh: line 19: /usr/data/backup/mysql/2022-04-28_150941.sql.gz: No such file or directory” abnormal
   The error is , The path in the backup script , stay Linux There is no... In the system , This is the time , You need to create the corresponding directory , The file is generated automatically .

3、 Create a scheduled task

Complete the above steps , The script is created , And can be used normally , The following is to create a scheduled task .
stay Linux In the system , perform “crontab -e” command , Enter the scheduled task editing interface , Editing requires timed commands , As shown below ：

After editing and saving , Check the following tasks ：