虽然我有3块显示屏幕，一般很少返回桌面，但还是掩不住ubuntu桌面单调的事实。Windows store有一个dynamic theme应用，可以自动抓取bing每日壁纸，并设置为桌面壁纸。简单搜了下，实现类似功能不难，思路也很简单。

python 爬虫抓取bing壁纸

爬虫一半的工作就是分析需要的数据怎么获取，所幸bing的非常简单，用来入门爬虫也挺好。打开https://cn.bing.com, F12分析源码，直接在head就能看到这样一句：

 <link id="bgLink" rel="preload" href="/th?id=OHR.RhodesIsland_ZH-CN0674840850_1920x1080.jpg&rf=LaDigue_1920x1080.jpg&pid=hp" as="image">

把href的链接和https://cn.bing.com拼接，浏览器打开即可看到我们所需的图片

 https://cn.bing.com/th?id=OHR.RhodesIsland_ZH-CN0674840850_1920x1080.jpg

爬虫主体代码实际只有10行，直接上：

 import re, requestsbing_url = 'https://cn.bing.com/'#保存图片路径path ='/home/yew/Pictures/spider/bing/'      #获取bing首页信息，headers是选填，本例应该不需要设置，但还是建议填上，后面补上配置response_text = requests.get(bing_url, headers=headers()).text#利用正则表达式查找url地址，目前只有2天测试可行，后续如果bing的结构不太一样可以调整，思路一样的url = re.findall('', response_text)#re.findall 返回的是list，name用于保存图片时命名name = re.findall('id=.*?\.(.*?)_', url[0])pic_url = 'https://cn.bing.com' + url[0]#保存图片pic = requests.get(pic_url, headers=headers())with open(path+name[0], 'wb') as f:    f.write(pic.content)

python爬虫向网站请求信息时携带自己的信息默认是python，明摆着告诉服务器我是爬虫，显然很容易被封，这时需要伪装自己是浏览器，随便打开一个网页F12-Network 选中一项查看Headers可以看到：

 user-agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) snap Chromium/83.0.4103.106 Chrome/83.0.4103.106 Safari/537.36

本例中设置headers = header(如下)即可，毕竟一天才爬一次，一次才一张图，对于服务器压力可以说忽略不计。

 header = {    'User-Agent':'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) snap Chromium/83.0.4103.106 Chrome/83.0.4103.106 Safari/537.36'}

不过我们后续还可能连续频繁爬其它内容，每次换user-agent让服务器认为我们是从不同浏览器访问的显然会更好一点。以下内容大篇幅user-agent，可以跳过

 import random, timedef headers():    USER_AGENTS = [    "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; AcooBrowser; .NET CLR 1.1.4322; .NET CLR 2.0.50727)",    "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0; Acoo Browser; SLCC1; .NET CLR 2.0.50727; Media Center PC 5.0; .NET CLR 3.0.04506)",    "Mozilla/4.0 (compatible; MSIE 7.0; AOL 9.5; AOLBuild 4337.35; Windows NT 5.1; .NET CLR 1.1.4322; .NET CLR 2.0.50727)",    "Mozilla/5.0 (Windows; U; MSIE 9.0; Windows NT 9.0; en-US)",    "Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Win64; x64; Trident/5.0; .NET CLR 3.5.30729; .NET CLR 3.0.30729; .NET CLR 2.0.50727; Media Center PC 6.0)",    "Mozilla/5.0 (compatible; MSIE 8.0; Windows NT 6.0; Trident/4.0; WOW64; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; .NET CLR 1.0.3705; .NET CLR 1.1.4322)",    "Mozilla/4.0 (compatible; MSIE 7.0b; Windows NT 5.2; .NET CLR 1.1.4322; .NET CLR 2.0.50727; InfoPath.2; .NET CLR 3.0.04506.30)",    "Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN) AppleWebKit/523.15 (KHTML, like Gecko, Safari/419.3) Arora/0.3 (Change: 287 c9dfb30)",    "Mozilla/5.0 (X11; U; Linux; en-US) AppleWebKit/527+ (KHTML, like Gecko, Safari/419.3) Arora/0.6",    "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.2pre) Gecko/20070215 K-Ninja/2.1.1",    "Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN; rv:1.9) Gecko/20080705 Firefox/3.0 Kapiko/3.0",    "Mozilla/5.0 (X11; Linux i686; U;) Gecko/20070322 Kazehakase/0.4.5",    "Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.0.8) Gecko Fedora/1.9.0.8-1.fc10 Kazehakase/0.5.6",    "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/535.11 (KHTML, like Gecko) Chrome/17.0.963.56 Safari/535.11",    "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_7_3) AppleWebKit/535.20 (KHTML, like Gecko) Chrome/19.0.1036.7 Safari/535.20",    "Opera/9.80 (Macintosh; Intel Mac OS X 10.6.8; U; fr) Presto/2.9.168 Version/11.52",    "Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10_6_8; en-us) AppleWebKit/534.50 (KHTML, like Gecko) Version/5.1 Safari/534.50",    "Mozilla/5.0 (Windows; U; Windows NT 6.1; en-us) AppleWebKit/534.50 (KHTML, like Gecko) Version/5.1 Safari/534.50",    "Mozilla/5.0 (Windows NT 10.0; WOW64; rv:38.0) Gecko/20100101 Firefox/38.0",    "Mozilla/5.0 (Windows NT 10.0; WOW64; Trident/7.0; .NET4.0C; .NET4.0E; .NET CLR 2.0.50727; .NET CLR 3.0.30729; .NET CLR 3.5.30729; InfoPath.3; rv:11.0) like Gecko",    "Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0)",    "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.0; Trident/4.0)",    "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0)",    "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1)",    "Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:2.0.1) Gecko/20100101 Firefox/4.0.1",    "Mozilla/5.0 (Windows NT 6.1; rv:2.0.1) Gecko/20100101 Firefox/4.0.1",    "Opera/9.80 (Macintosh; Intel Mac OS X 10.6.8; U; en) Presto/2.8.131 Version/11.11",    "Opera/9.80 (Windows NT 6.1; U; en) Presto/2.8.131 Version/11.11",    "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_7_0) AppleWebKit/535.11 (KHTML, like Gecko) Chrome/17.0.963.56 Safari/535.11",    "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; Maxthon 2.0)",    "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; TencentTraveler 4.0)",    "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1)",    "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; The World)",    "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; Trident/4.0; SE 2.X MetaSr 1.0; SE 2.X MetaSr 1.0; .NET CLR 2.0.50727; SE 2.X MetaSr 1.0)",    "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; 360SE)",    "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; Avant Browser)",    "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1)",    "Mozilla/5.0 (iPhone; U; CPU iPhone OS 4_3_3 like Mac OS X; en-us) AppleWebKit/533.17.9 (KHTML, like Gecko) Version/5.0.2 Mobile/8J2 Safari/6533.18.5",    "Mozilla/5.0 (iPod; U; CPU iPhone OS 4_3_3 like Mac OS X; en-us) AppleWebKit/533.17.9 (KHTML, like Gecko) Version/5.0.2 Mobile/8J2 Safari/6533.18.5",    "Mozilla/5.0 (iPad; U; CPU OS 4_3_3 like Mac OS X; en-us) AppleWebKit/533.17.9 (KHTML, like Gecko) Version/5.0.2 Mobile/8J2 Safari/6533.18.5",    "Mozilla/5.0 (Linux; U; Android 2.3.7; en-us; Nexus One Build/FRF91) AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1",    "MQQBrowser/26 Mozilla/5.0 (Linux; U; Android 2.3.7; zh-cn; MB200 Build/GRJ22; CyanogenMod-7) AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1",    "Opera/9.80 (Android 2.3.4; Linux; Opera Mobi/build-1107180945; U; en-GB) Presto/2.8.149 Version/11.10",    "Mozilla/5.0 (Linux; U; Android 3.0; en-us; Xoom Build/HRI39) AppleWebKit/534.13 (KHTML, like Gecko) Version/4.0 Safari/534.13",    "Mozilla/5.0 (BlackBerry; U; BlackBerry 9800; en) AppleWebKit/534.1+ (KHTML, like Gecko) Version/6.0.0.337 Mobile Safari/534.1+",    "Mozilla/5.0 (hp-tablet; Linux; hpwOS/3.0.0; U; en-US) AppleWebKit/534.6 (KHTML, like Gecko) wOSBrowser/233.70 Safari/534.6 TouchPad/1.0",    "Mozilla/5.0 (SymbianOS/9.4; Series60/5.0 NokiaN97-1/20.0.019; Profile/MIDP-2.1 Configuration/CLDC-1.1) AppleWebKit/525 (KHTML, like Gecko) BrowserNG/7.1.18124",    "Mozilla/5.0 (compatible; MSIE 9.0; Windows Phone OS 7.5; Trident/5.0; IEMobile/9.0; HTC; Titan)",    "UCWEB7.0.2.37/28/999",    "NOKIA5700/ UCWEB7.0.2.37/28/999",    "Openwave/ UCWEB7.0.2.37/28/999",    "Mozilla/4.0 (compatible; MSIE 6.0; ) Opera/UCWEB7.0.2.37/28/999",    ]    header = {        'User-Agent': random.choice(USER_AGENTS),        #多次爬取同一个网站可能会达到连接最高限制，设置连接完成后马上断开        'Connection': 'close',      }    return(header)

user-agent可以自己慢慢收集补充进去。在爬取小站时，建议time.sleep(0.5+random())，避免给人家服务器造成太大压力，也避免自己被封。想快速抓取，可以多线程+代理IP等，目前我还没需求，没研究。

设置自动更换壁纸

设置自动变壁纸有两个文件，以ubuntu20为例：

 /usr/share/gnome-background-properties/focal-wallpapers.xml/usr/share/backgrounds/contest/focal.xml

后者配置自动切换的图片及频率，前者指定后者位置，写入系统配置。

观察后者配置，发现它非常简单，就是将/usr/share/backgrounds里的图片路径配置进去，每半小时切换一次。我们可以手动将图片地址换上去即可，不过这太繁琐了，后续爬取图片多了得累死，所以模仿它格式写个bash(确保文件夹内至少2张图片，否则自动更换没意义了)

 #文件路径/home/yew/git/crontab/bing_backgrounds_xml.sh#!/bing/bash#爬取图片存放地址path=/home/yew/Pictures/spider/bingfiles=`ls -U $path`last_file='empty'echo ''echo ' 'echo '   2020'echo '   04'echo '   01'echo '   00'echo '   00'echo '   00'echo ' 'for current_file in $filesdo    if [[ $last_file == 'empty' ]]    then        last_file=$current_file        echo ' '        #可以根据爱好更改切换时间        echo '   1795.0'        echo "   $path/$last_file"        echo ' '    else        echo ' '        echo '    5.0'        echo "    $path/$last_file"        echo "    $path/$current_file"        echo ' '        echo ' '        echo '   1795.0'        echo "   $path/$current_file"        echo ' '        last_file=$current_file    fidoneecho ''                          

运行一下，生成xml文件

 bash /home/yew/git/crontab/bing_backgrounds_xml.sh > /home/yew/git/crontab/bing_backgrounds.xml

在上述focal-wallpapers.xml中添加配置如下：

 <wallpapers> <wallpaper deleted="false">   <name>Ubuntu 20.04 Community Wallpapersname>   <filename>/home/yew/git/crontab/bing_backgrounds.xmlfilename>   <options>zoomoptions> wallpaper>  <wallpaper deleted="false">   <name>Ubuntu 20.04 Community Wallpapersname>   <filename>/usr/share/backgrounds/contest/focal.xmlfilename>   <options>zoomoptions> wallpaper>

此时桌面空白处右键更改桌面背景就可以看到第一个选项出现了bing图，并且右下角有个小时钟图标，选中即可。

每日计划执行

还有一个问题，bing图需要每日抓取，抓取的新图也需要添加到自动更换配置中，这里用到linux的crontab命令

 crontab -e #进入计划任务编辑模式#每日10点10分运行爬虫抓取图片，如果有标准/错误输出扔掉10 10 * * * /usr/bin/python3 /home/yew/git/python/spider/bing_pic.py >/dev/null 2>&1#每日10点24分生成新的自动切换壁纸xml文件24 10 * * * /bin/bash /home/yew/git/crontab/bing_backgrounds_xml.sh > /home/yew/git/crontab/bing_backgrounds.xml

one more thing

一直觉得vi使用很别扭，搜索才发现ubuntu预装的是vim tiny，会出现按方向键是ABCD，ctrl+V变成^等问题，解决办法如下：

 sudo apt remove vim-common #卸载vim-tinysudo apt install vim  #安装vim full