55 lines
2.9 KiB
Markdown
55 lines
2.9 KiB
Markdown
# Scrawl
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Scrawl is a simple command line tool for downloading files referenced on websites using [CSS
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selectors](http://www.w3schools.com/cssref/css_selectors.asp). This application is not meant to be a replacement for
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[curl](http://curl.haxx.se/) or [Wget](https://www.gnu.org/software/wget/), but rather a precision tool for grabbing
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files when the context in which they are presented is known to. This capability is particularly useful when the path of
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the desired file is not known but the URL of the website that links to it is (common for download pages).
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## Installation
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If you already have the Go environment and toolchain set up, you can get the latest version by running:
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```
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$ go install foosoft.net/projects/scrawl@latest
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```
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Otherwise, you can use the [pre-built binaries](https://github.com/FooSoft/scrawl/releases) from the project page.
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## Usage
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Executing Scrawl with the `-help` command line argument will trigger online help to be displayed. Below is a more
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detailed description of what the parameters do.
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* `attr`: The attribute containing the desired download path is specified by this argument.
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* `dir`: This argument specifies the output directory for downloaded files.
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* `vebose`: Scrawl will output more details about what it is currently doing when this flag is set.
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## Example
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Let's say we want to create a script to download the latest Debian package of [Anki](http://ankisrs.net/):
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1. We load up the homepage and are presented with a big download button as shown in the screenshot below: \
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2. Let's copy that link so we can download the latest version with wGet or curl from our script at any time! Hmm, it
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looks like the path `http://ankisrs.net/download/mirror/anki-2.0.33.deb` has the version number embedded in the
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filename. This means that even after a new version of Anki is released, our script will keep getting version
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`2.0.33` (unless of course it gets deleted).
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3. Let's inspect the download link in your favorite browser to see what additional information we can get: \
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4. It appears that we can easily create a selector for this element: `#linux > a:nth-child(2)`. Note that
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[Chrome](https://www.google.com/chrome/) provides the option to copy the CSS selector for any element, making
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knowledge of web technology optional for this step.
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5. Now let's create a simple download and install script:
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```bash
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#!/bin/sh
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rm -rf /tmp/anki
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mkdir /tmp/anki
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scrawl -attr=href -dir=/tmp/anki -verbose http://ankisrs.net/ "#linux > a:nth-child(2)"
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sudo dpkg -i /tmp/anki/*.deb
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sudo apt-get install -y -f
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```
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In this script, we prepare an empty download directory and tell Scrawl to scrape `http://ankisrs.net/`, extracting
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the `href` property of the download link identified by the CSS selector `#linux > a:nth-child(2)`. We then install
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the package and bring in any unsatisfied dependencies.
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