半吊子的技术

这个脚本可以放进crontab，每天凌晨执行一次，自动备份所有mysql数据库。   这个脚本每天最多只执行一次，而且只保留最近五天的备份在服务器上。
脚本中，默认mysql安装目录在/usr/local/mysql/下，如果你的mysql不在此目录，请修改脚本mysql命令文件位置。
默认我把脚本建立在/etc/mysql_backup.sh

#vim /etc/mysql_backup.sh

编辑文件内容：

#!/bin/sh 
# mysql_backup.sh: backup mysql databases and keep newest 5 days backup. 
# 
# Last updated: 20 March 2006 
# ---------------------------------------------------------------------- 
# This is a free shell script under GNU GPL version 2.0 or above 
# Copyright (C) 2006 Sam Tang 
# Feedback/comment/suggestions : http://www.real-blog.com/ 
# ---------------------------------------------------------------------- 
# your mysql login information 
# db_user is mysql username 
# db_passwd is mysql password 
# db_host is mysql host 
# ----------------------------- 
db_user="root" 
db_passwd="password" 
db_host="localhost" 
# the directory for story your backup file. 
backup_dir="/home/mybackup" 
# date format for backup file (dd-mm-yyyy) 
time="$(date +"%d-%m-%Y")" 
# mysql, mysqldump and some other bin's path 
MYSQL="/usr/local/mysql/bin/mysql" 
MYSQLDUMP="/usr/local/mysql/bin/mysqldump" 
MKDIR="/bin/mkdir" 
RM="/bin/rm" 
MV="/bin/mv" 
GZIP="/bin/gzip" 
# check the directory for store backup is writeable 
test ! -w $backup_dir && echo "Error: $backup_dir is un-writeable." && exit 0 
# the directory for story the newest backup 
test ! -d "$backup_dir/backup.0/" && $MKDIR "$backup_dir/backup.0/" 
# get all databases 
all_db="$($MYSQL -u $db_user -h $db_host -p$db_passwd -Bse 'show databases')" 
for db in $all_db 
do 
$MYSQLDUMP -u $db_user -h $db_host -p$db_passwd $db | $GZIP -9 > "$backup_dir/backup.0/$time.$db.gz" 
done 
# delete the oldest backup 
test -d "$backup_dir/backup.5/" && $RM -rf "$backup_dir/backup.5" 
# rotate backup directory 
for int in 4 3 2 1 0 
do 
if(test -d "$backup_dir"/backup."$int") 
then 
next_int=`expr $int + 1` 
$MV "$backup_dir"/backup."$int" "$backup_dir"/backup."$next_int" 
fi 
done 
exit 0; 

赋予该文件执行权限

#chmod 755 /etc/mysql_backup.sh

默认数据备份路径/home/mybackup,因为写入权限问题，新建该文件夹，并赋予777权限

#mkdir /home/mybackup
#chmod 777 /home/mybackup

最后，将本脚本代入crontab自动执行

#crontab -e

添加如下代码（每日23点59分自动执行）

59 23 * * * /etc/mysql_backup.sh