使用bash随机更换壁纸

所需工具

wget: 下载URL和壁纸图片
grep: 从URL中抽取指向壁纸的URL
feh: 设置壁纸到桌面上
shuf: 产生随机效果

壁纸的来源

为了简便处理，我们只从 https://www.reddit.com/r/wallpapers/ 的第一页中随机选取壁纸。

实现步骤

用浏览器打开 https://www.reddit.com/r/wallpapers/ 你就会发现它列出了最新产生的25个帖子。

点开帖子就会显示出具体的壁纸内容来

所以我们要做的其实就是下面几步：

从 https://www.reddit.com/r/wallpapers/ 中抽取出帖子的链接
随机选择一个帖子链接
找出帖子链接中图片的URL
下载并设置壁纸

从 https://www.reddit.com/r/wallpapers/ 中抽取出帖子的链接

首先让我们用 wget 下载 https://www.reddit.com/r/wallpapers/ 页面来分析一下该如何抽取出帖子的链接呢。

wget  https://www.reddit.com/r/wallpapers -O -

这条命令会下载 https://www.reddit.com/r/wallpapers/ 页面然后将内容显示在标准输出中。

由于内容太多，这里就不列出具体的内容了。我们先把网页中所有的链接过滤出来看看都有哪些内容.

wget  https://www.reddit.com/r/wallpapers -O - |grep -o -E 'href="([^"#]+)"' |sort |uniq

href="/"
href="http://redditgifts.com/"
href="http://s1.1zoom.me/b5555/619/Ireland_Castles_Trim_castle_Night_Shrubs_538153_2560x1440.jpg"
href="https://about.reddit.com"
href="https://about.reddit.com/advertise/"
href="https://about.reddit.com/careers/"
href="https://about.reddit.com/press/"
href="https://i.imgur.com/0eSNAHv.jpg"
href="https://i.imgur.com/3tPGErY.jpg"
href="https://i.imgur.com/hs7OcfD.jpg"
href="https://i.imgur.com/pIYPQQZ.jpg"
href="https://imgur.com/a/qLnxOv1"
href="https://imgur.com/a/zR2iLXL"
href="https://reddit.com/message/compose?to=/r/wallpapers"
href="https://www.reddit.com/gold/about"
href="https://www.reddit.com/help/contentpolicy"
href="https://www.reddit.com/help/healthycommunities/"
href="https://www.reddit.com/help/privacypolicy"
href="https://www.reddit.com/help/useragreement"
href="https://www.reddit.com/login?redirect=https%3A%2F%2Fwww.reddit.com%2Fr%2Fwallpapers%2F"
href="https://www.reddit.com/mobile/download"
href="https://www.reddit.com?redirect=https%3A%2F%2Fwww.reddit.com%2Fr%2Fwallpapers%2F"
href="https://www.reddit.com/register?redirect=https%3A%2F%2Fwww.reddit.com%2Fr%2Fwallpapers%2F"
href="https://www.reddit.com/r/wallpapers/"
href="https://www.reddit.com/r/wallpapers/?after=t3_8e2rq7"
href="https://www.reddit.com/r/wallpapers/comments/8e2rq7/rush_downtown_thebadbadben_2732x1536/"
href="https://www.reddit.com/r/wallpapers/comments/8e7k5i/ghost_in_the_shell/"
href="https://www.reddit.com/r/wallpapers/comments/8eaglp/tripy_leaf_wallpaper_edited_from_an_unsplash_image/"
href="https://www.reddit.com/r/wallpapers/comments/8eapkd/beautiful_purple_sunset_1920x180/"
href="https://www.reddit.com/r/wallpapers/comments/8ebjj0/credit_to_whoever_took_this_picture_i_forget/"
href="https://www.reddit.com/r/wallpapers/comments/8ebyo5/another_whale_seen_in_the_sky_2880x1800/"
href="https://www.reddit.com/r/wallpapers/comments/8ebyvm/snowy_hills_3840_2160/"
href="https://www.reddit.com/r/wallpapers/comments/8edl5j/vaporwave_hills_3840x2160/"
href="https://www.reddit.com/r/wallpapers/comments/8efq4z/3d_city_glitch_1920x1080/"
href="https://www.reddit.com/r/wallpapers/comments/8eica4/my_cat/"
href="https://www.reddit.com/r/wallpapers/comments/8eiuhx/imperial_walkers_dawn_darek_zabrocki_3235x1820/"
href="https://www.reddit.com/r/wallpapers/comments/8ej0ev/kratos_1366x768/"
href="https://www.reddit.com/r/wallpapers/comments/8ej8np/in_the_woods_the_blue_gloom_m_yakovlev_4373x2460/"
href="https://www.reddit.com/r/wallpapers/comments/8ek3ab/sr71_amidst_the_sunset_3072x1728/"
href="https://www.reddit.com/r/wallpapers/comments/8ekaf2/tokyo_rose_vice_2412x1357/"
href="https://www.reddit.com/r/wallpapers/comments/8ekb2n/another_personal_favorite_cerebrum_by_tomasz/"
href="https://www.reddit.com/r/wallpapers/comments/8ekqe8/zettai_ryouiki_outrun_a_sr71_colonel_cbplayer/"
href="https://www.reddit.com/r/wallpapers/comments/8ekwjg/boardwalk_1920_1080/"
href="https://www.reddit.com/r/wallpapers/comments/8elgzr/venom_1688x1076/"
href="https://www.reddit.com/r/wallpapers/comments/8enilg/lighthouse_2560x1440/"
href="https://www.reddit.com/r/wallpapers/comments/8ep7de/trim_castle_ireland_2500_x_1440/"
href="https://www.reddit.com/r/wallpapers/comments/8epjah/nekopara_vol_0_sfw_1920x1202/"
href="https://www.reddit.com/r/wallpapers/comments/8er6uk/apollo_17_earths_moon_2560x1440/"
href="https://www.reddit.com/r/wallpapers/comments/8ess6s/planet_surfaces/"
href="https://www.reddit.com/r/wallpapers/comments/8et1sk/stars_space_galaxy_1920x1080/"
href="https://www.reddithelp.com"
href="https://www.redditstatic.com/desktop2x/Commons.a1e39474b980de9725ef.js"
href="https://www.redditstatic.com/desktop2x/fonts/IBMPlexSans/Medium-c4b185e25a4dde85a29f902cd5ce5360.woff2"
href="https://www.redditstatic.com/desktop2x/fonts/IBMPlexSans/Regular-116bb6d508f5307861d3b1269bc597e7.woff2"
href="https://www.redditstatic.com/desktop2x/img/favicon/android-icon-192x192.png"
href="https://www.redditstatic.com/desktop2x/img/favicon/apple-icon-114x114.png"
href="https://www.redditstatic.com/desktop2x/img/favicon/apple-icon-120x120.png"
href="https://www.redditstatic.com/desktop2x/img/favicon/apple-icon-144x144.png"
href="https://www.redditstatic.com/desktop2x/img/favicon/apple-icon-152x152.png"
href="https://www.redditstatic.com/desktop2x/img/favicon/apple-icon-180x180.png"
href="https://www.redditstatic.com/desktop2x/img/favicon/apple-icon-57x57.png"
href="https://www.redditstatic.com/desktop2x/img/favicon/apple-icon-60x60.png"
href="https://www.redditstatic.com/desktop2x/img/favicon/apple-icon-72x72.png"
href="https://www.redditstatic.com/desktop2x/img/favicon/apple-icon-76x76.png"
href="https://www.redditstatic.com/desktop2x/img/favicon/favicon-16x16.png"
href="https://www.redditstatic.com/desktop2x/img/favicon/favicon-32x32.png"
href="https://www.redditstatic.com/desktop2x/img/favicon/favicon-96x96.png"
href="https://www.redditstatic.com/desktop2x/img/favicon/manifest.json"
href="https://www.redditstatic.com/desktop2x/overlap-2c2efe7e95ba8fc991854e8f01322243.575c42d246b39a3a03e6.js"
href="https://www.redditstatic.com/desktop2x/overlap-44e3d536a182a3fe6c9eed5014e47b05.08362281f54b63e55856.js"
href="https://www.redditstatic.com/desktop2x/overlap-617df21ac848fad21f5733296c4f91a1.e7da3e4bc28c59fb8ef1.js"
href="https://www.redditstatic.com/desktop2x/overlap-9fc0f7a006faf347e6dc6a1670421fb0.6d15f53ff4128ba2c408.js"
href="https://www.redditstatic.com/desktop2x/overlap-de8e488af5f659d52a5c321db16a89a5.f1cd898dc044a4d81f48.js"
href="https://www.redditstatic.com/desktop2x/overlap-fc592e99099d1804afeb090c87b920c0.6a46ccff54a4bc09e93c.js"
href="https://www.redditstatic.com/desktop2x/ProductionVendorAux.b93c16e76c66f5775359.js"
href="https://www.redditstatic.com/desktop2x/ProductionVendor.f98cdff1b7e8856c5548.js"
href="https://www.redditstatic.com/desktop2x/Reddit.3ae165fca313f57c16bb.js"
href="http://www.redditblog.com/"
href="/r/all"
href="/r/popular"
href="/r/wallpapers/"
href="/r/wallpapers"
href="/r/wallpapers/comments/8e2rq7/rush_downtown_thebadbadben_2732x1536/"
href="/r/wallpapers/comments/8e7k5i/ghost_in_the_shell/"
href="/r/wallpapers/comments/8eaglp/tripy_leaf_wallpaper_edited_from_an_unsplash_image/"
href="/r/wallpapers/comments/8eapkd/beautiful_purple_sunset_1920x180/"
href="/r/wallpapers/comments/8ebjj0/credit_to_whoever_took_this_picture_i_forget/"
href="/r/wallpapers/comments/8ebyo5/another_whale_seen_in_the_sky_2880x1800/"
href="/r/wallpapers/comments/8ebyvm/snowy_hills_3840_2160/"
href="/r/wallpapers/comments/8edl5j/vaporwave_hills_3840x2160/"
href="/r/wallpapers/comments/8efq4z/3d_city_glitch_1920x1080/"
href="/r/wallpapers/comments/8eica4/my_cat/"
href="/r/wallpapers/comments/8eiuhx/imperial_walkers_dawn_darek_zabrocki_3235x1820/"
href="/r/wallpapers/comments/8ej0ev/kratos_1366x768/"
href="/r/wallpapers/comments/8ej8np/in_the_woods_the_blue_gloom_m_yakovlev_4373x2460/"
href="/r/wallpapers/comments/8ek3ab/sr71_amidst_the_sunset_3072x1728/"
href="/r/wallpapers/comments/8ekaf2/tokyo_rose_vice_2412x1357/"
href="/r/wallpapers/comments/8ekb2n/another_personal_favorite_cerebrum_by_tomasz/"
href="/r/wallpapers/comments/8ekqe8/zettai_ryouiki_outrun_a_sr71_colonel_cbplayer/"
href="/r/wallpapers/comments/8ekwjg/boardwalk_1920_1080/"
href="/r/wallpapers/comments/8elgzr/venom_1688x1076/"
href="/r/wallpapers/comments/8enilg/lighthouse_2560x1440/"
href="/r/wallpapers/comments/8ep7de/trim_castle_ireland_2500_x_1440/"
href="/r/wallpapers/comments/8epjah/nekopara_vol_0_sfw_1920x1202/"
href="/r/wallpapers/comments/8er6uk/apollo_17_earths_moon_2560x1440/"
href="/r/wallpapers/comments/8ess6s/planet_surfaces/"
href="/r/wallpapers/comments/8et1sk/stars_space_galaxy_1920x1080/"
href="/r/wallpapers/controversial/"
href="/r/wallpapers/hot/"
href="/r/wallpapers/new/"
href="/r/wallpapers/rising/"
href="/r/wallpapers/submit"
href="/r/wallpapers/top/"
href="/user/acoolrocket"
href="/user/Aileos"
href="/user/Arcade23"
href="/user/BradFMB"
href="/user/campymountain"
href="/user/Clinicalyabrasiv"
href="/user/CreamSodaFloat"
href="/user/Donutsen"
href="/user/douglasrcjames"
href="/user/emem01"
href="/user/hero0fwar"
href="/user/KorvisKhan"
href="/user/MrAwkwardCrotch"
href="/user/nothingsaidalice"
href="/user/pakaau"
href="/user/PiekarnikCiepla"
href="/user/pmaxm00"
href="/user/sequence_string"
href="/user/T3DS"
href="/user/T-D-S"
href="/user/ThatOnePhotog"
href="/user/thmanwithnoname"
href="/user/thmodwithnoname"
href="/user/xypnox"
href="/user/zaron5551"

你会发现结果中包含了很多乱七八糟的链接。我们还有必要做进一步的过滤。

通过分析这些帖子的URL，可以看出它们都是以 https://www.reddit.com/r/wallpapers/comments 开头的。因此我们试着用 grep 将符合这个条件的URL过滤出来看看效果怎么样

wget  https://www.reddit.com/r/wallpapers -O - |grep -o -E 'href="([^"#]+)"' |grep -o -E 'https://www.reddit.com/r/wallpapers/comments/[^"]+/'

https://www.reddit.com/r/wallpapers/comments/8efq4z/3d_city_glitch_1920x1080/
https://www.reddit.com/r/wallpapers/comments/8e7k5i/ghost_in_the_shell/
https://www.reddit.com/r/wallpapers/comments/8ebjj0/credit_to_whoever_took_this_picture_i_forget/
https://www.reddit.com/r/wallpapers/comments/8ebyvm/snowy_hills_3840_2160/
https://www.reddit.com/r/wallpapers/comments/8eapkd/beautiful_purple_sunset_1920x180/
https://www.reddit.com/r/wallpapers/comments/8edl5j/vaporwave_hills_3840x2160/
https://www.reddit.com/r/wallpapers/comments/8ebyo5/another_whale_seen_in_the_sky_2880x1800/
https://www.reddit.com/r/wallpapers/comments/8eaglp/tripy_leaf_wallpaper_edited_from_an_unsplash_image/
https://www.reddit.com/r/wallpapers/comments/8e2rq7/rush_downtown_thebadbadben_2732x1536/
https://www.reddit.com/r/wallpapers/comments/8efhr9/all_our_gods_have_abandoned_us_architectsuk/
https://www.reddit.com/r/wallpapers/comments/8e3qbh/remember_this_always_loved_this_wallpaper_from/
https://www.reddit.com/r/wallpapers/comments/8e4ni5/long_past_civlization_4000_2349/
https://www.reddit.com/r/wallpapers/comments/8e6281/bus/
https://www.reddit.com/r/wallpapers/comments/8e2c57/fluid_mechanics_beeple_3840x2160/
https://www.reddit.com/r/wallpapers/comments/8e5j95/tulips_at_5_am_1920x1280/
https://www.reddit.com/r/wallpapers/comments/8e3r13/a_deer_in_the_forest_1920x1080/
https://www.reddit.com/r/wallpapers/comments/8e62jt/froggo/
https://www.reddit.com/r/wallpapers/comments/8e4xv5/abstract_swirls_2560x1600/
https://www.reddit.com/r/wallpapers/comments/8dvuro/samurai_spiral_1536_x_864/
https://www.reddit.com/r/wallpapers/comments/8e1j0g/blossom_wallpaper_shot_by_me/
https://www.reddit.com/r/wallpapers/comments/8dy02y/lagoon_nebula/
https://www.reddit.com/r/wallpapers/comments/8e4t9z/wallpaper_for_multi_screen_setup/
https://www.reddit.com/r/wallpapers/comments/8do356/living_tree_4000_2400/
https://www.reddit.com/r/wallpapers/comments/8dviei/ruined_canvas/
https://www.reddit.com/r/wallpapers/comments/8dvzwe/infinity_gauntlet_3840x2160/

过滤结果非常好!

随机选择一个链接

要随机选择链接，我们可以使用 shuf 命令来打乱链接的顺序，然后选择第一个链接作为我们要访问的链接就行了

wget  https://www.reddit.com/r/wallpapers -O - |grep -o -E 'href="([^"#]+)"' |grep -o -E 'https://www.reddit.com/r/wallpapers/comments/[^"]+/' |shuf -n 1

https://www.reddit.com/r/wallpapers/comments/8ej8np/in_the_woods_the_blue_gloom_m_yakovlev_4373x2460/

找出帖子链接中图片的URL

按照之前的方法，我们来看看帖子链接中都有哪些链接。不过由于我们只需要图片，因此可以加个限制只显示包含 .jpg, .jpeg, 或者 .png 的URL.

url=$(wget  https://www.reddit.com/r/wallpapers -O - |grep -o -E 'href="([^"#]+)"' |grep -o -E 'https://www.reddit.com/r/wallpapers/comments/[^"]+/' |shuf -n 1)
wget ${url} -O - |grep -o -E 'href="([^"#]+)"' |grep -E "\.jpg|\.jpeg|\.png"

href="https://www.redditstatic.com/desktop2x/img/favicon/apple-icon-57x57.png"
href="https://www.redditstatic.com/desktop2x/img/favicon/apple-icon-60x60.png"
href="https://www.redditstatic.com/desktop2x/img/favicon/apple-icon-72x72.png"
href="https://www.redditstatic.com/desktop2x/img/favicon/apple-icon-76x76.png"
href="https://www.redditstatic.com/desktop2x/img/favicon/apple-icon-114x114.png"
href="https://www.redditstatic.com/desktop2x/img/favicon/apple-icon-120x120.png"
href="https://www.redditstatic.com/desktop2x/img/favicon/apple-icon-144x144.png"
href="https://www.redditstatic.com/desktop2x/img/favicon/apple-icon-152x152.png"
href="https://www.redditstatic.com/desktop2x/img/favicon/apple-icon-180x180.png"
href="https://www.redditstatic.com/desktop2x/img/favicon/android-icon-192x192.png"
href="https://www.redditstatic.com/desktop2x/img/favicon/favicon-32x32.png"
href="https://www.redditstatic.com/desktop2x/img/favicon/favicon-96x96.png"
href="https://www.redditstatic.com/desktop2x/img/favicon/favicon-16x16.png"
href="https://i.redditmedia.com/Ii0AWUY-N8ibB4bNA0g20PPlNcSc8-nC3kQBlXiT3UA.jpg?s=fb92a5cd0a6d82cb423f87bd3f876b27"
href="https://resi.ze-robot.com/dl/3d/3d-city-glitch-1920×1080.jpg"
href="https://resi.ze-robot.com/dl/3d/3d-city-glitch-1600×900.jpg"
href="https://resi.ze-robot.com/dl/3d/3d-city-glitch-1366×768.jpg"
href="https://resi.ze-robot.com/dl/3d/3d-city-glitch-1280×720.jpg"
href="https://resi.ze-robot.com/dl/3d/3d-city-glitch-1280×800.jpg"
href="https://resi.ze-robot.com/dl/3d/3d-city-glitch-1024×768.jpg"
href="https://resi.ze-robot.com/dl/3d/3d-city-glitch-1280×1024.jpg"
href="https://resi.ze-robot.com/dl/3d/3d-city-glitch-768×1024.jpg"
href="https://i.redd.it/yt2lweavmqt01.jpg"

其中 redditstatic 中的图片是reddit本身的那些图片，而 resi.ze=robot.com 中的图片是提供下载的不同尺寸的地址，我们过滤掉这两个地址

url=$(wget  https://www.reddit.com/r/wallpapers -O - |grep -o -E 'href="([^"#]+)"' |grep -o -E 'https://www.reddit.com/r/wallpapers/comments/[^"]+/' |shuf -n 1)
wget ${url} -O - |grep -o -E 'href="([^"#]+)"' |grep -E "\.jpg|\.jpeg|\.png" |grep -v -E "www.redditstatic.com|resi.ze-robot.com"

href="https://i.imgur.com/0eSNAHv.jpg"
href="https://i.imgur.com/0eSNAHv.jpg"
href="https://i.imgur.com/0eSNAHv.jpg"
href="https://i.imgur.com/nFZpEAo.png"
href="https://i.imgur.com/0eSNAHv.jpg"

还可能剩下多张图片，我们再用 shuf 来随机选择其中一张

url=$(wget  https://www.reddit.com/r/wallpapers -O - |grep -o -E 'href="([^"#]+)"' |grep -o -E 'https://www.reddit.com/r/wallpapers/comments/[^"]+/' |shuf -n 1)
wget ${url} -O - |grep -o -E 'href="([^"#]+)"' |grep -E "\.jpg|\.jpeg|\.png" |grep -v -E "www.redditstatic.com|resi.ze-robot.com" |shuf -n 1

href="https://i.imgur.com/u7Wm6aB.jpg"

我们把URL从 href 中抽取出来

url=$(wget  https://www.reddit.com/r/wallpapers -O - |grep -o -E 'href="([^"#]+)"' |grep -o -E 'https://www.reddit.com/r/wallpapers/comments/[^"]+/' |shuf -n 1)
wget ${url} -O - |grep -o -E 'href="([^"#]+)"' |grep -E "\.jpg|\.jpeg|\.png" |grep -v -E "www.redditstatic.com|resi.ze-robot.com" |shuf -n 1 |grep -o -E 'http[^"]+'

https://i.redd.it/iihqrt3zmft01.png

下载并设置壁纸

我们使用wget来下载壁纸，并通过feh来设置壁纸。

不过有一点需要注意的是，我们上一步中假设壁纸是以 .jpg, .jpeg, 或者 .png 结尾的。那如果壁纸不是以这三个后缀结尾怎么办？一个简单的办法就是重新再随机选择一次。

#!/bin/bash

function get_image_url()
{
    url=$(wget  https://www.reddit.com/r/wallpapers -O - |grep -o -E 'href="([^"#]+)"' |grep -o -E 'https://www.reddit.com/r/wallpapers/comments/[^"]+/' |shuf -n 1)
    wget ${url} -O - |grep -o -E 'href="([^"#]+)"' |grep -E "\.jpg|\.jpeg|\.png" |grep -v -E "www.redditstatic.com|resi.ze-robot.com" |shuf -n 1 |grep -o -E 'http[^"]+'
}

image_url=$(get_image_url)

while [[ -z "${image_url}" ]];do
    image_url=$(get_image_url)
done

wget ${image_url} -O - |feh --bg-scale -

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