Get a subset of lines from a big text file using PowerShell v2

Question

I\'m working with a big text file, I mean more than 100 MB big, and I need to loop through a specific number of lines, a kind of subset so I\'m trying with this,

<

Answer 1

Are the rows of fixed length? If they are, you can seek to desired position by simply calculating offset*row length and using something like .Net FileStream.Seek(). If they are not, all you can do is to read file row by row.

To extract lines m, n, try something like

# Open text file
$reader = [IO.File]::OpenText($myFile)
$i=0
# Read lines until there are no lines left. Count the lines too
while( ($l = $reader.ReadLine()) -ne $null) {
    # If current line is within extract range, print it
    if($i -ge $m -and $i -le $n) {
        $("Row {0}: {1}" -f $i, $l)
    }
    $i++
    if($i -gt $n) { break } # Stop processing the file when row $n is reached.
}
# Close the text file reader
$reader.Close()
$reader.Dispose()