Use wget to download / scrape a full website

Summary

This video tutorial introduces the use of 'wget', a simple tool for downloading and scraping websites. It demonstrates basic usage, advanced functionalities, and common parameters for web scraping or file downloading. The video provides step-by-step examples, including downloading an entire website's content for offline access, with parameters to handle recursion, resource downloading, and domain restrictions. It also covers best practices for large-scale scraping, such as wait times and rate limiting, to avoid IP blacklisting and ensure efficient data retrieval.

Takeaways

• 😀 The video introduces the use of Wget as a simple tool for downloading and scraping websites.
• 🔍 The script outlines three examples of using Wget, starting with a basic example and moving to more advanced functionalities.
• 📚 It is clarified that 'scraping' in this context may not involve in-depth data extraction but more about downloading web pages for offline use.
• 🌐 The video mentions other tools like Scrapy for more advanced scraping capabilities, which have been covered in other videos.
• 📁 The first example demonstrates downloading a simple HTML file using Wget, which can be opened in a browser but lacks other resources.
• 🔄 The second example introduces parameters like recursive navigation, no-clobber, page requisite, convert links, and domain restrictions to download associated resources.
• 🚀 The third example includes advanced parameters for handling larger sites, such as wait times between requests, rate limiting, user-agent specification, recursion levels, and logging progress.
• 🛠 The script emphasizes the need to adjust parameters based on the specific requirements of the site being scraped.
• 🔒 It highlights the importance of respecting website policies and being a considerate 'netizen' when scraping to avoid IP blacklisting.
• 📝 The video concludes with a note on the utility of Wget for quick scraping tasks and post-processing of content offline.

Q & A

What is the main purpose of the video?

The main purpose of the video is to demonstrate how to use Wget as a simple tool to download and scrape an entire website.

What are the three examples outlined in the video?

The video outlines three examples: 1) A basic example similar to a 'hello world', 2) Advanced functionality with common parameters used for screen scraping or downloading files, and 3) More advanced parameters for more complex scenarios.

What does the term 'download and scrape' imply in the context of the video?

In the context of the video, 'download and scrape' implies downloading the webpage content and extracting structured content from the web pages, although the video emphasizes that it is a simple example and not an in-depth scraping capability.

What are some limitations of using Wget for scraping?

Some limitations of using Wget for scraping include that it might not extract all content such as CSS files, images, and other resources by default, and it is not as versatile as full-fledged web scraping tools.

What is the significance of the 'no-clobber' parameter in Wget?

The 'no-clobber' parameter in Wget ensures that if a page has already been crawled and a file has been created, it won't crawl and recreate that page, which is helpful for avoiding duplication and managing connectivity issues.

How does the 'page-requisites' parameter in Wget affect the download process?

The 'page-requisites' parameter in Wget ensures that all resources associated with a page, such as images and CSS files, are also downloaded, making the content more complete for offline use.

What is the purpose of the 'convert-links' parameter in Wget?

The 'convert-links' parameter in Wget is used to convert the links in the downloaded pages to point to local file paths instead of pointing back to the server, making the content accessible for offline browsing.

Why is the 'no-parent' parameter used in Wget?

The 'no-parent' parameter in Wget is used to restrict the download process to the specified hierarchy level, ensuring that it does not traverse up to higher levels such as parent directories or different language versions of the site.

What are some advanced parameters discussed in the video for handling larger websites?

Some advanced parameters discussed for handling larger websites include 'wait' to introduce a delay between requests, 'limit-rate' to control the download speed, 'user-agent' to mimic a browser, 'recursive' to control the depth of recursion, and redirecting output to a log file.

How can Wget be used to monitor website changes?

Wget can be used to download webpages and keep the content offline, which can then be used for comparison over time to monitor if websites have changed, although the video does not detail specific methods for this monitoring.

Outlines

00:00

🌐 Introduction to Using Wget for Website Downloading and Scraping

The video introduces the use of Wget, a simple tool for downloading and scraping websites. The presenter outlines the plan to demonstrate three examples: a basic example akin to a 'hello world', advanced functionality, and more complex parameters. The purpose is to show how to keep a website offline or scrape parts of it. The presenter clarifies that Wget is not primarily for in-depth scraping but for downloading web pages for offline use or local processing. They also mention other tools like Scrapy for more advanced scraping capabilities.

05:01

🔍 Advanced Wget Parameters for Comprehensive Website Scraping

This paragraph delves into more advanced parameters of Wget for scraping websites. The presenter discusses the use of recursive navigation to crawl through a site like a web crawler, the 'no-clobber' option to avoid re-crawling pages, and the 'page-requisites' parameter to download all associated resources like images and CSS. The 'convert-links' and 'convert-file-only' options are highlighted for local file path linking and character escaping. The presenter also emphasizes the importance of restricting the download to a specific domain or subdomain to avoid downloading external resources unintentionally.

10:04

🛠️ Enhancing Wget Efficiency with Rate Limiting and User-Agent Customization

The final paragraph focuses on enhancing Wget's efficiency and etiquette when scraping larger sites. The presenter suggests using a delay between requests to avoid IP blacklisting and a rate limit to control the download speed. They also mention the importance of specifying a user agent to mimic a browser, which can be crucial for sites that check for familiar user agents. The default recursion depth is discussed, along with the option to adjust it for deeper or shallower crawling. The presenter concludes with a demonstration of running Wget in the background and logging the output to a file, which is useful for monitoring progress over time.

Keywords

💡Wget

Wget is a free utility for non-interactive download of files from the web. It supports HTTP, HTTPS, and FTP protocols, and is often used for downloading web pages for offline viewing or scraping. In the video, Wget is used to demonstrate how to download and scrape content from websites, making it a central tool in the discussion.

💡Web scraping

Web scraping is the process of extracting data from websites. It involves programmatically accessing the content of web pages and extracting information from them. In the video, the concept is introduced as a way to extract content from web pages using Wget, although the speaker clarifies that Wget is not primarily a scraping tool but can be used for basic scraping tasks.

💡Recursion

In the context of web scraping, recursion refers to the process of following links on a webpage to discover and download additional pages. The video mentions using recursion with Wget to navigate through a website and download its content, simulating the behavior of a web crawler.

💡No clobber

The 'no clobber' option in Wget prevents the program from overwriting existing files with the same name. In the video, this option is used to ensure that if a page has already been downloaded, it will not be re-downloaded and overwritten, which can be useful during development or testing phases.

💡HTML

HTML, or HyperText Markup Language, is the standard language used for creating web pages. The video script discusses downloading HTML files using Wget, which is a fundamental aspect of web scraping as it allows users to access the structure and content of web pages.

💡CSS

CSS, or Cascading Style Sheets, is used for describing the presentation of a document written in HTML. The video mentions that while Wget can download HTML files, it might not always download associated CSS files, which can affect the appearance of the downloaded pages when viewed offline.

💡Images

Images are a common element of web pages that may be downloaded during web scraping. The video script discusses the limitations of Wget in downloading images, especially when they are hosted on different domains, highlighting the need for additional parameters to ensure comprehensive content downloading.

💡User agent

The user agent is a string that identifies the software, operating system, and vendor of the requester agent to the accessed server. In the video, the speaker mentions that some websites might block requests from unfamiliar user agents, suggesting that specifying a user agent can be a strategy to avoid being blocked during web scraping.

💡Rate limit

A rate limit in web scraping is a constraint on the number of requests that can be made to a server in a given period. The video script suggests using a rate limit with Wget to avoid overwhelming the server and potentially getting the IP address blacklisted.

💡Log file

A log file is a record of events that occur in a system. In the context of the video, Wget can be configured to output its progress to a log file, which is useful for monitoring the status of a download or scrape operation, especially when running in the background.

Highlights

Introduction to using Wget as a simple tool for downloading and scraping websites.

Three examples outlined: a basic example, advanced functionality, and more advanced parameters.

Clarification that 'download and scrape' may have different implications but focuses on simple Wget usage.

Comparison with other tools like Scrapy for more advanced capabilities.

Demonstration of using Wget to download a simple HTML file from a website.

Explanation of limitations such as not downloading CSS, images, and other resources by default.

Introduction to advanced parameters like recursive navigation and no-clobber option.

Use of page requisite, convert links, and domain restrictions for more comprehensive scraping.

Demonstration of a complete website download including HTML and associated resources.

Discussion on the importance of adjusting parameters for different websites and scraping needs.

Introduction of additional parameters for handling larger sites, such as wait time and rate limiting.

Explanation of user agent specification to avoid being detected as a bot.

Demonstration of running Wget in the background with log file output for monitoring progress.

Note on the use of random wait times for more effective scraping on certain sites.

Final note on the quick and dirty nature of Wget compared to full-fledged web scraping tools.

Conclusion and thanks for watching the video on using Wget for downloading and scraping websites.

Transcripts

hi everyone in this video we'll take a

look at how we can use W get as a simple

tool to download and enter website slash

scrape an entire website now for

purposes of keeping this video really

short and simple try to outline three

examples we'll take a look at a basic

example kind of like a hello world if

you will and then we'll take a look at

some more advanced functionality will

kind of like go through a very common

set of scenarios or parameters that we

won't use for screen scraping or

downloading files off of a website and

then finally we'll take a look at some

more advanced parameters now I do want

to clarify that when when we talk about

download and scrape it might have

different implications but keep in mind

that this is a very simple example of

using W get I've covered other tools

like scrap IR and even off-the-shelf

scraping tools in the channel so you

might want to take a look at that for

more advanced capability so but this is

probably the simplest way how you can

download or keep a site offline or even

scrape some parts of the site so I say

squid with a bit of a hesitation because

in most cases when you talk about scrape

you're talking about extracting content

from webpages that's basically crawling

the web pages and passing the web pages

and taking content or structured content

from the web page and storing that in

some other structured way or you know

kind of like extracting information from

web pages so just want to emphasize that

this video is not really an in-depth

scraping capability it's not something

you used W get for it's more of a case

that you want to download the video

I'm sorry download the web page and then

keep the website content offline or do

some for the processing locally on your

desk or you can build other tools to

monitor if websites have changed etc so

we are going to exclusively use W gate

tool so a lot of the parameters

of Webjet if that's unclear or you want

to investigate further you can head over

to this URL and all of this is in the

description of the video below to get

started let's start off with a simple

example I've taken a random website

I say random in the sense that the

tongue-in-cheek because I'm pointing

into scrap I which is one of the tools

have covered in an earlier video

incidentally scrappy is is a web

scraping tool as an open-source web

scraping tool so it's kind of funny

we're using web get to scrape or

download scrappy anyway that wasn't the

original web site I had in mind but I

thought it would be interesting from a

video demo standpoint anyway so let's

actually go and see oops what the

website looks like if I can get rid of

web get yeah yeah all right so this is

basically the content that we are trying

to extract in all of these examples you

might argue that this isn't the best

example there are hardly any images here

except them but again I wanted a simple

site for a demo feel free to substitute

this URL with your preferred one all

right so let's let's head over to the

console let me just just copy that again

and on our console I'm gonna just I've

created a folder which currently does

not contain anything and let's just

paste that the web get Oh would be

helpful if I na

all right so connection established

let's try that again

alright so what you saw was the the web

get in action but it didn't do anything

amazing it's just downloaded a simple

HTML file which if you open obviously

opens up on the browser here and you can

see that it's pointing to a local

resource now keep in mind that not all

the contents of this page are extracted

and pulled down to your computer so for

example

CSS files JPEG images etc these are

downloaded which actually brings us to

the next example so this was you know

just a very simple example if you've

never used web gait for HTML chances are

you've used web get in the past to

download zip files and other software

installation files but interesting to

think of it as a tool to download

webpages now things get more interesting

in example two here we are going to use

a few parameters here so the first thing

we'll want to do you'll notice that I'm

pointing into the same folder so I am

sorry the same URI what I've specified

here is that it needs to recursively

navigate the contents of this initial

page and then start recursively

traversing through the site more like a

web crawler would do this is not a

mandatory option but the no clobber

basically implies that if if a page if a

URL had already been crawl and if a page

was created don't crawl and recreate

that page so it's typically helpful when

you have issues with connectivity or you

want to stop and restart a couple of

times so typically during development or

testing this is where things get more

interesting so we have the page

requisite so remember I talked about in

this particular case and we extracted it

the first time it was just the HTML but

it did not download or keep an offline

copy of any of the other resources like

images and CSS etc so setting this will

ensure that all the other resources are

also downloaded HTML extension base is

helpful when your navigator when you're

crawling scraping and downloading files

which typically have an extension like

JSP or ASP X or CGI scripts which when

you want to store on your local file and

when you hard disk and when you want to

click on it you want the extension to be

an HTML extension so that it

automatically opens in the browser

so that's the only reason for this

convert lengths basically and sure

that any links HTML anchor or various

others linked to a local file path as

opposed to pointing it back to the

server you are eyes that's basically

what a convert link is and finally we

have some escaping of characters and

finally this what you're seeing is we

are specifying that it needs to only

stay within the domain or the sub domain

and finally no parent specifies that it

needs to be at this hierarchy level and

it'll ensure that it does not go up a

hierarchy say for example into French or

German language so let's run this

example now alright so if we run that

example let me just cancel that and

clear that folder just so that it stays

clean and we know what's going on all

right so that's now you can see that

it's a completely scraped downloaded all

these pages and if we go down here

you'll notice we have the index dot HTML

page so let me close the old one and now

this is our latest downloaded page now

just be mindful that while this

selection of mine might not it's

actually a poor choice of a website that

I've used for this video because this

page does still rely on external CSS

files and various external resources and

since we have locked it down to only the

scrappy org domain it's not going to

download those resources locally

additionally you'll find that if you try

to copy it from the same site or follow

the same example you don't notice some

of the images haven't been downloaded

because this is an example of an image

that in a different

domaine so we have restricted it to only

be in scrappy dot org domain whereas

this is trying to point to read the docs

that aughh domain so again it depends on

your particular mileage of how much you

want to scrape but I'm just highlighting

that based on the parameters you

provided here it may or may not scrape

the content to the fullest degree and

keep everything offline but obviously

you can kind of like tweak these

parameters to your heart's content

now just a quick temp given where we are

right now what we have done is we have

downloaded the files it's it's all there

in our local hard disk and that's

brilliant it's kind of allows for us to

do offline browsing /do for the

processing offline but in most cases

you're you are trying to download or

scrape a much larger site typically

these parameters alone will not suffice

so in which case that's typically where

I use the third example here now this

has some additional parameters here so

in in most cases you'll definitely want

to keep these parameters so in in the

previous examples you you've noticed

that the requests were being sent

immediately one after the other and this

is OK for small sites or if you are

scraping only a small subset but when

you're scraping larger sites they might

blacklist your IP so one of the ways you

can get around that or just be a good

netizen if you will is to allow for a

wait so it waits for five seconds before

it it sends the next request also you

can specify a rate limit so how much of

beta you're downloading so by default

it's bytes so you can specify the key or

I believe you can also specify the M as

in megabytes parameter so again it

ensures that your sites don't get

blacklisted and some sites are a little

more intelligent it it checks that the

user agent is not in a familiar list so

it might not serve you content so there

are ways that you can specify the user

agent and then finally there are ways

that the default keep in mind recursive

again you can check the docs for more

up-to-date information but you'll find

that the default recursion I believe is

only five levels deep but if you did

want to recurse down to lower levels or

restrict it to something less like maybe

two for example you can set the level

here and the last thing I will point out

is in most cases when I'm downloading a

larger website I typically would want to

run it in the background but at the same

point in time have a log file where I

can send that data to so W get provides

some inbuilt functionality so we can

send the output or see what the process

or progress is in kind of like a log

file and we will run it in the

background

so let's take a look at that in action

and just before I do that let me just

split this into two sections here so

that we can see the files

let's run that here all right so that's

running in the background if if you take

a look you'll notice that I up it's a

it's the process is still running in the

background and we have sent the data to

this file here so if I look at the

contents you notice here we have a new

file here so let's tell the activity so

here we can see the log is being updated

as and when new requests and progress is

made we our web get it's sending the

results to the log file so I can just

you know close all this consoles and

maybe come back in a couple of hours or

maybe even much longer if it does take

that long

and then I'll see what the progress is

so that's quite handy here I would say

in vast majority of the cases this is a

kind of like template that I would use

one final note before we wrap up for

this video is again you'll want to run

it on different sites and see how it

performs but some sites do do know that

there's a bot you know an automated

process that's working or making these

requests so instead of having a fixed

five-second wait you can remove this

wait and instead put this which is a

random wait which works on some sites

again it's a this has a tool it's a

quick and dirty in a manner of speaking

and it's not as versatile as a

full-fledged web scraping tool obviously

again I've covered these in other videos

in the past some other examples of web

scripting tools but just something I

found quite handy when I wanted to

scrape off some some content really

quickly and keep it either offline I'll

do some post processing and content

extraction all right so that's it for

this quick video thanks everyone for

watching