Kiron

Use Get-Content's -ReadCount parameter, set it to 1 to send a line at a time
through the pipeline but don't assign this to a variable before, instead
redirect the output to a file, e.g.:

gc c:\largeFile.txt -read 1 | ? {<filters>} > c:\filteredFile.txt

# don't assign the out to variable like this
$filterContent = gc c:\largeFile.txt -read 1 | ? {<filters>}

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Kiron