Scribbles for my bad memory

通常 A 机器和 B 机器已经在 ~/.ssh/config 中定义并建立了信任关系，因此我们可以直接使用主机别名，而不需要使用 user@B_machine 的方式。

sync_files.sh 脚本

#!/bin/bash

# 定义源和目标目录
SOURCE_DIR="/data/files/"
DEST_DIR="B_machine:~/backups/A_machine/data/files"

# 执行 rsync 命令
rsync -av --exclude='tmp/' "$SOURCE_DIR" "$DEST_DIR"

1. 确保脚本有执行权限：

   chmod +x sync_files.sh
   

2. 使用 cron 设置每五分钟执行一次该脚本：

   crontab -e
   

   添加：

   */5 * * * * /path/to/sync_files.sh
   

1. on a server with huge disk space, run crontab -e and put the following code in it (you may need to change the directory names to fit your situation)

30 3 * * * mysqldump --databases DB1 DB2 DB3 DB4 | gzip > /data/backups/mysql/db_`date '+\%Y\%m\%d-\%H\%M\%S'`.sql.gz
30 4 * * * find /data/backups/mysql/db_* -mtime -1 -exec scp {} anotherserver:/data/backups/mysql \;
30 5 * * * find /data/backups/mysql/db_* -mtime +30 -exec rm {} \;

2. on another server, run crontab -e and put the following line into it:

30 5 * * * find /data/backups/mysql/db_* -mtime +7 -exec rm {} \;

summary & explanation:

1. at 3:30 backup MySQL data in a local directory and keep latest 30 days backup in that directory
2. at 4:30 transfer the latest backup to another server in case the first backup may be destroyed by an accident.
3. at 5:30 remove the oldest backup on the local backup server (the code shows that the latest 30 days backups are kept on the server).
4. at 5:30 remove the oldest backup on the remote server (the code shows that only the latest 7 days backups are kept on that server).