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流程控制
if语句
- 单分支if语句
程序 fi``` ```if [ 判断 ] then 程序 fi```
实例代码脚本:
#!/bin/bash
#Author: haiyang
#提取sda3分区的使用率给rate
rate = $(df -h | grep "/dev/sda3" | awk {'print $5'} | cut -f1 -d "%")
if [ $rate -ge 80 ]
then
echo "Warning! /dev/sda3 is full!"
fi
- 双分支判断
if [ 判断 ]
then
程序
else
另一个程序
fi
实现脚本,备份数据库
#!/bin/bash
#备份数据
#Author:haiyang
#得到当前系统时间
date=$(date + %y%m%d)
#得到数据库大小
size=$(du -sh /var/lib/mysql)
if [ -d /tmp/dbbak ]
then
echo "Date : $date!" > /tmp/dbbak/dbinfo.log
echo "Size : $size! " > /tmp/dbbak/dbinfo.log
cd /tmp/dbbak
tar -zcf mysql-lib-$date.tar.gz /var/lib/mysql dbinfo.log &>/dev/null
rm -rf /tmp/dbback/dbinfo.log
else
mkdir /tmp/dbbak
echo "Date : $date!" > /tmp/dbbak/dbinfo.log
echo "Size : $size! " > /tmp/dbbak/dbinfo.log
cd /tmp/dbbak
tar -zcf mysql-lib-$date.tar.gz /var/lib/mysql dbinfo.log &>/dev/null
rm -rf /tmp/dbback/dbinfo.log
fi