removing multiline blocks from a text file based on a pattern

PowerShell Help
1

Hello. I have a text file that looks like this:
{
“something” “else”
“even” “2”
“moretext” “704 1696 -40”
}
{
“text” “random”
“odd” “1”
“never” “more”
}
…

Basically it’s a series of multiline blocks enclosed in curly brackets. There can be any number of line between the brackets.
What I need is to search this file for a string and if the string is found then remove the block(s) in curly brackets (including them) that contain it. So for example if I search for ‘more’, it should delete the whole block:
{
“text” “random”
“odd” “1”
“never” “more”
}
If I search for ‘1’, it should remove both blocks.

I’m sure it can be done with regex, but my regex skills are too low and I can’t figure this out.
Any help is appreciated.

2

Short answer:

$($(get-content sample.txt) -join '').split('}').trimstart('{') | where-object {$_ -notlike "*random*"}

long answer:
get-content will import your text file with each line as an item in an array.

get-content sample.txt

{
"something" "else"
"even" "2"
"moretext" "704 1696 -40"
}
{
"text" "random"
"odd" "1"
"never" "more"
}

Step one would be to use -join to make one long string out of the input.

$(get-content sample.txt) -join ''

{"something" "else""even" "2""moretext" "704 1696 -40"}{"text" "random""odd" "1""never" "more"}

Step 2 would be to then turn that string back into an array by splitting on the closing curly brace.

$($(get-content sample.txt) -join '').split('}')

{"something" "else""even" "2""moretext" "704 1696 -40"
{"text" "random""odd" "1""never" "more"

Step 3 we clean up the opening curly brace

$($(get-content sample.txt) -join '').split('}').trimstart('{')

"something" "else""even" "2""moretext" "704 1696 -40"
"text" "random""odd" "1""never" "more"

Step 4 we use where-object to filter out any items that have the magic word

$($(get-content sample.txt) -join '').split('}') | where-object {$_ -notlike "*random*"}

"something" "else""even" "2""moretext" "704 1696 -40"
3

Jeremy, thank you,that works.
I need to preserve the original file format though (haven’t mentioned that explicitly above), how can I achieve that with your code?

4

Hi John,

You should use a RegEx like this:

{(.|\n)?more(.|\n)?}

In this case if it finds the word “more” it will mark the whole text within {}; however, it matches even part of the word as well. In your example, it will select both since the first group has the word “moretext” and the second one “more”

5

Leandro, I’m not getting any matches using your regex. Maybe because Get-Content loads the file as array of lines?
edit: but yes, it should include partial matches too, my example above was incorrect, I didn’t notice both block contained ‘more’

6

Yeah, Get-Content reads the file as an array and the regex works for a full text per say; try doing a

Get-Content -Path FILE_PATH -Raw
7

You are going to run into a problem where it crosses multiple blocks with the {(.|\n)?more(.|\n)?} pattern.

For example: {(.|\n)?never(.|\n)?} matches

{
"something" "else"
"even" "2"
"moretext" "704 1696 -40"
}
{
"text" "random"
"odd" "1"
"never" "more"
}

Rather than just

{
"text" "random"
"odd" "1"
"never" "more"
}

What I would do is first find all of my blocks, then filter out the ones I don’t want, then join all the remaining blocks back together.

Somthing like this:

cls
$exclude = "odd"
((Get-Content -Path "D:\New Text Document.txt" -Raw | Select-String -Pattern "(?s)\{.*?\}" -AllMatches).matches.value | Select-String -Pattern $exclude -NotMatch) -join "`n"
8

One more for your consideration…

$RandomData = @’
{
“something” “else”
“even” “2”
“A new record” “704 1696 -40”
}
{
“something” “else”
“even” “2”
“I want this one” “704 1696 -40”
}
{
“text” “random”
“odd” “1”
“never” “more”
}
{
“something” “else”
“even” “2”
“moretext” “704 1696 -40”
}
{
“text” “random”
“odd” “1”
“never” “And this one also”
}
{
“something” “else”
“even” “2”
“moretext” “704 1696 -40”
}
{
“something” “else”
“even” “2”
“The last record” “704 1696 -40”
}
'@

Remove all record entries taht match the string ‘more’

Validate pattern match

$RandomData -match ‘.[^]\b[^?{](.more.)\b(.|\n)?}*}’

True

Get all matches

{
“text” “random”
“odd” “1”
“never” “more”
}
{
“something” “else”
“even” “2”
“moretext” “704 1696 -40”
}
{
“something” “else”
“even” “2”
"m

Remove matches from the the data

$RandomData -replace ‘.[^]\b[^?{](.more.)\b(.|\n)?}*}’

{
“something” “else”
“even” “2”
“A new record” “704 1696 -40”
}
{
“something” “else”
“even” “2”
“I want this one” “704 1696 -40”
}
{
“text” “random”
“odd” “1”
“never” “And this one also”
}
{
“something” “else”
“even” “2”
“The last record” “704 1696 -40”
}

9

Nice, I never even considered using -replace, but it makes a lot of sense.

Here is another regex that could be used with -replace and takes less steps to process.

$exclude = "odd"
(Get-Content -Path "D:\New Text Document.txt" -Raw) -replace "{[^\}]*$exclude[^\}]*}(\r\n|\n)"
10

Thanks everyone for the input. I went with Curtis’ code in the end, works well.
At least I got some regexes to study.