Shell 流程控制－if 语句

if [ 条件判断式 ] ; then
程序
fi

例子：判断分区使用率

#!/bin/bash
# Author: huangrui (Email:[email protected])

rate=$(df -h | grep "sda1" | awk ‘{print $5}‘ | cut -f 1 -d "%")

if [ $rate -gt 80 ]; then
   echo "Warning! disk is full !!!"
fi

Code

例子：备份网站目录文件

#!/bin/bash
# Author huangrui (Email:[email protected])

date=$(date +%y%m%d)
size=$(du -sh /home/test.com)

if [ -d /home/test.com ];then
    echo "date is :$date" > /tmp/dbback/db.txt
    echo "size is :$size" >> /tmp/dbback/db.txt
    cd /tmp/dbback
    tar -zcf web_$date.tar.gz /home/test.com db.txt&>/dev/null
    rm -rf /tmp/dbback/db.txt
else
    mkdir /tmp/dbback
    echo "date is :$date" > /tmp/dbback/db.txt
    echo "size is :$size" >> /tmp/dbback/db.txt
    cd /tmp/dbback
    tar -zcf web_$date.tar.gz /home/test.com db.txt&>/dev/null
    rm -rf /tmp/dbback/db.txt
fi

Code

判断apache是否启动，使用nmap命令

#!/bin/bash
# Author huangrui (Email:[email protected])

port=$(nmap -sT 172.16.193.128 | grep tcp | grep http | awk ‘{print $2}‘)

if [ "$port" == "open" ]; then
   echo "$(date) httpd is ok!" >> /tmp/autostart-acc.log
else
   /etc/rc.d/init.d/httpd restart &>/dev/null
   echo "$(date) httpd is restart!!" >> /tmp/autostart-err.log
fi

Code