Extract string using Powershell between two points of reference

Question

I am trying to extract a string of data from text file that I downloaded using EWS. I am using powershell to do this. A snippet of the file is as follows.

<table class="button" style="border-collapse: collapse; border-spacing: 0; overflow: 
hidden; padding: 0; text-align: left; vertical-align: top; width: 100%;"><tbody>
<tr style="padding: 0; text-align: left; vertical-align: top;"><td style="-moz-hyphens: none; 
-webkit-hyphens: none; -webkit-text-size-adjust: none; background: #049FD9; 
border: none; border-collapse: collapse !important; border-radius: 2px; color: #fff; display: block; font-family: 'Helvetica-Light','Arial',sans-serif; font-size: 14px; font-weight: lighter; hyphens: none; line-height:19px; margin: 0; padding: 8px 16px; text-align: center; vertical-align: top; width: auto 
!important; word-break: keep-all;">
<a href="https://www.website.com:443/idb/setPassword?t=BcHJEoIgAADQD%2BKQjqZ4VEKtBHLJJm82uWDuxCR%2Bfe%2B58Rl9HRz6QddWkO5MLDXuF6e9m%2Bo0z%2FCVS%2B9IenAp5m5yTfYRa%2BAn4jdWHHF7HTyqRZiRRiNDEE%2BK7ZJywLKeNCTj4ewu4QNu02qXB0ZTXTyxXADwaLeluZGVPCxGXunpVcHbiCVAWRR7ykqGensLVBsqNUpl%2FQE%3D" 
style="-webkit-text-size-adjust: none; font-weight: 100; color: #fff; font-family: 'Helvetica-Light','Arial',sans-serif; font-size: 20px; font-weight: lighter; line-height: 32px; text-decoration: none;">Get Started</a> </td></tr></tbody></table></td>

I want to extract this part BcHJEoIgAADQD%2BKQjqZ4VEKtBHLJJm82uWDuxCR%2Bfe%2B58Rl9HRz6QddWkO5MLDXuF6e9m%2Bo0z%2FCVS%2B9IenAp5m5yTfYRa%2BAn4jdWHHF7HTyqRZiRRiNDEE%2BK7ZJywLKeNCTj4ewu4QNu02qXB0ZTXTyxXADwaLeluZGVPCxGXunpVcHbiCVAWRR7ykqGensLVBsqNUpl%2FQE%3D

I've tried -matches and using regex lookbehinds and forwards but nothing seems to be able to grab that part only.

Thought something like this might work

$a = Get-Content $path 
$a -match '(?<=setPassword\?t\=)(.+)(?=" style)' 

$matches

But it comes up blank

'SomePrefixAnyString'.Substring('SomePrefix'.Length) should result to AnyString. — JosefZ
– JosefZ, Commented May 1, 2017 at 17:01
Thanks, problem is I dont know what AnyString is. Its always something different. which is why I have to have a starting point and an ending point and grab anything in between. I'm thinking its gotta be some sort of regex...maybe — Jason Murray
– Jason Murray, Commented May 1, 2017 at 17:25

briantist · Accepted Answer · 2017-05-01 17:09:43Z

4

Best not to use string manipulation for this; use existing libraries and classes.

So first of all, treat your URI as a [uri]:

$uri = [System.Uri]'https://www.website.com/idb/setPassword?t=BcHJEoIgAADQD%2BKQjqZ4VEKtBHLJJm82uWDuxCR%2Bfe%2B58Rl9HRz6QddWkO5MLDXuF6e9m%2Bo0z%2FCVS%2B9IenAp5m5yTfYRa%2BAn4jdWHHF7HTyqRZiRRiNDEE%2BK7ZJywLKeNCTj4ewu4QNu02qXB0ZTXTyxXADwaLeluZGVPCxGXunpVcHbiCVAWRR7ykqGensLVBsqNUpl%2FQE%3D'

Now you can get the query string like this:

$query = $uri.Query

That will start with ?t=, so let's parse it:

$queryData = [System.Web.HttpUtility]::ParseQueryString($query)

The resulting object has a set of keys, one for each value. Since the key you want is called t, you can get the value like this:

$queryData['t']

answered May 1, 2017 at 17:09

briantist

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5 Comments

Jason Murray Over a year ago

Thanks for the answer, not sure if this will work because I have to know the URL to start out with. Each link that comes in is different everytime. The only thing that is constant in the link is the website.com/idb/setPassword?t= and the closing quote to the link " So thats why I was needing to be able to search for those to points of reference to extract that long string in between.

briantist Over a year ago

@JasonMurray why would that prevent this from working? This method specifically doesn't depend on the URL; the only assumption is that the query parameter you want has a key of t. Just take the string that contains the URL and cast is as [System.Uri] as shown, or use the -as operator. The example is only hardcoding the string because that's what you supplied.

Jason Murray Over a year ago

Ah I see what you mean it does work. The issue is I need to pull that full URL out of html/text data that I pulled from exchange which is the body of the email. All that data is set to a variable that I should be able to read from. So I need some way to pull that URL from the data and then parse it like you show to get the info after the t=

briantist Over a year ago

@JasonMurray well.. that's outside the scope of your question, but I would recommend parsing the HTML with HtmlAgilityPack.

Jason Murray Over a year ago

Updated the question to reflect more of what I was needing an answer on...thanks

Jason Murray · Accepted Answer · 2017-05-02 11:56:40Z

0

So I figured out the text document I was outputting to was word wrapping part of the long URL. I ended up outputting with the -Width command so it wouldn't do that.

$email | Out-File $path -Width 9999999

Then I ended up using matches to grab the string I needed using.

$a = Get-Content $path | Where-Object {$_ -match '(?<=https:\/\/www\.website\.com:443\/idb\/setPassword\?t=)(.+)(?=" style)'}
$matches[1]

Hope that helps someone.

answered May 2, 2017 at 11:56

Jason Murray

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