How to copy only sentences between two headings - powershell

Question

I have a text file in which it has lots of headings and a few sentences below it.
I have wanted to search for the heading and if the heading is available I want to copy sentences below the heading till next heading.
Is it possible in PowerShell please help me I tried
$linenumber= Get-Content "C:\Users\KSYEDSU\Documents\temp\4491309.txt" | select-string $search
Select-String $string $dataRead -Context 1, $linenumber| % { $_.Context.PostContext } | out-file "C:\Users\KSYEDSU\Documents\temp\Results.txt"
But it is throwing an error telling it is expecting interger
$linenumber= Get-Content "C:\Users\KSYEDSU\Documents\temp\4491309.txt" | select-string $search
Select-String $string $dataRead -Context 1, $linenumber| % { $_.Context.PostContext } | out-file "C:\Users\KSYEDSU\Documents\temp\Results.txt"
ex:
Heading A
1234
34545
13213
Heading B
So I will search for Heading A and if it is available then start copying from 1234... till 13213.

Answer 1

Select-String will find the string inside your text but does not return the position as int. You could loop trough your file and look manueally for the heading and collect the data between.
#Get file content as string array
[System.String[]]$FileContent = Get-Content -Path 'C:\Users\KSYEDSU\Documents\temp\4491309.txt'
#For each line in the file
for ($i = 0; $i -lt $FileContent.Count; $i ++)
{
#If the line equals your start header
if ($FileContent[$i] -eq 'Heading A')
{
$i ++ #Get the next line
#Return line until end header appears
while ($FileContent[$i] -ne 'Heading B')
{
$FileContent[$i] #Return line
$i ++ #Get next line
}
}
}

Answer 2

You could use regex to do this, so you don't have to loop through all lines in the text file:
$headingStart = 'Heading A'
$headingEnd = 'Heading B'
# get the file content in one string, including all newline characters
$content = Get-Content "C:\Users\KSYEDSU\Documents\temp\4491309.txt" -Raw
# since the real headings may contain characters that have special meaning in regex, we escape them
$regex = '(?s)^{0}\s+(.*)\s{1}' -f [regex]::Escape($headingStart), [regex]::Escape($headingEnd)
if ($content -match $regex) {
$matches[1] | Out-File -FilePath "C:\Users\KSYEDSU\Documents\temp\Results.txt"
}
else {
Write-Host "No text found between $headingStart and $headingEnd"
}
Using your example, the resulting file will contain:
1234
34545
13213

Answer 3

You can use a switch statement combined with the -Regex and -File flags.
$insideHeaders = $false
. {switch -Regex -File "C:\Users\KSYEDSU\Documents\temp\4491309.txt" {
'Heading A' { $insideHeaders = $true }
'Heading B' { return }
default {
if ($insideHeaders) { $_ }
}
}} | Out-File "C:\Users\KSYEDSU\Documents\temp\Results.txt"
Explanation:
Each value between single quotes is a regex string. You will have to backslash (\) escape any special regex characters, which can be done automatically using [regex]::Escape(string).
When the bottom header (Heading B in this case) is reached, the return statement will exit the switch statement.
All lines not matching one of the headers will trigger the default condition. The default condition will only output a line if the first header has been found.