Download Bing Background Image Everyday by Python

Recently I read a translation version of a Quora Q&A in which people are talking about how the programmers use computer to serve their own life.
The translation version is: 看程序员是如何把自动化做到极致的！
And the initial Quora post is: As a programmer, what tasks have you automated to make your everyday life easier?

One engineer just mentioned he wrote a small program to download Bing background images everyday automatically by the computer. The images, which would be a new one everyday, are all great photographs token all over the world.

后来再尝试代码发现不行了。。。 2017.10

Recently, I start learning and using Python in my work. And I heard a lot about Python’s fantastic functionality in collecting data from the Internet.
So I think maybe I could do this as well.

A post on 知乎 can be a good intro on Python reptile for us beginners - 如何入门 Python 爬虫？.

See the Pictures

Now the program has been run for 3 times.

Following are the results!

Look great! Right?

Now let’s start to do the job!

First, Get the Picture

This time, I use urllib.request module.

import urllib.request
url = 'http://cn.bing.com/'  # Set url as Bing homepage
page = urllib.request.urlopen(url)
html = page.read().decode('utf-8')  # Get the raw HTML code of the page
# Get the url of the picture itself
# Following rules need to be recognised beforehand manually
a = html.find(r'g_img={url: "http:')
b = html.find(r'_1920x1080.jpg')
path = "/home/katherine/Pictures/"  # Set the target position to save the picture
img_url = html[(a+13):(b+14)].replace('\\','')  # Replce the '\\'s
name = img_url.rsplit('/')[-1]  # Use the raw name
conn = urllib.request.urlopen(img_url)
f = open(path+name,'wb')
f.write(conn.read())
f.close()  # Save the picture data
print('Pic Saved!')

Next, Ask PC to do Everyday Job

`crontab`

I searched and people say crontab could solve the problem and it’s already in Linux os.

Syntax is as below:

crontab [-u user] file
crontab [ -u user ] [ -i ] { -e | -l | -r }
-e	(edit user's crontab)
-l	(list user's crontab)
-r	(delete user's crontab)
-i	(prompt before deleting user's crontab)

Below is the syntax of crontab.

*   *   *   *   *   command to be executed
-   -   -   -   -
|   |   |   |   |
|   |   |   |   +----- day of week (0 - 6) (Sunday=0)
|   |   |   +------- month (1 - 12)
|   |   +--------- day of month (1 - 31)
|   +----------- hour (0 - 23)
+------------- min (0 - 59)

However, I failed…
Now I think maybe because I didn’t specify the user name.

`python-crontab`

Then I just find a python package called crontab which can do the same job.

Use pip install python-crontab to complete the installation.

from crontab import CronTab
cron = CronTab(user=True)
job = cron.new(command='python3 /home/katherine/PycharmProjects/untitled/bing_img.py')
job.minute.on(45)
job.hour.on(9)
cron.write()

After setting a crontab task, we can use crontab -l in Terminal to check.

Now we can see

1	45 9 * * * python3 /home/katherine/PycharmProjects/untitled/bing_img.py

which means 09:45 everyday, python3 would run bing_img.py.

If the computer is power off, the crontab will not work.

Next Step

Maybe in next step I can collect the description for the image everyday because I can tell no information only by looking at the beautiful pictures.
Or I could try other interesting tasks ;P