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How do I reverse the contents of a .txt file whilst preserving empty lines?

For example

text one



text two

text three



text four





text five





text six

would become

text six





text five





text four



text three

text two



text one

Preferably with the Windows console or also source code to compile from to an application. I have Windows 7.

This can be done easily with Powershell without any additional tools.

$x = Get-Content -Path data.txt; Set-Content -Path data.txt -Value ($x[($x.Length-1)..0])

Found the perfect tool for this: tac (part of CoreUtils for Windows)

Another powershell example. This just shows reversing. It would be trivial to export $x to a file.

$x = Get-Content -Path .abc.txt

[array]::Reverse($x)

$x

In most cases a typical sort wont preserve your empty lines but will instead place them all together somewhere in your sort. If it was me I'd just copy and paste the lines in excel and sort there if it's just some one-off thing. Otherwise you'll be getting into some really fancy scripting to do this (but hey, it's possible to do).

As for the script I'd first have some code that searches for blank lines and saves that location to an array. Then I'd sort the rest of the data, either using some built-in sort method or making my own "bubble sort" code. Once sorted, reintroduce the line breaks at the locations given and you'll be set.

I would read the file in reverse order (using a script, program, etc.) and write it to a 'new' file thus avoiding a sort. Then, delete the 'old' file and rename the 'new' one to the 'old' one.

Here's something native - a Visual Basic Script (.vbs).

Const ForReading = 1

Set objFSO = CreateObject("Scripting.FileSystemObject")

infile = Wscript.Arguments(0)

Set objTextFile = objFSO.OpenTextFile (infile, ForReading)

strText = objTextFile.ReadAll

objTextFile.Close

arrText = Split(strText, vbCrLf)

for l = ubound(arrText)-1 to 0 step -1

   wscript.echo arrText(l)

Next

save it as (e.g.) revfile.vbs and run it using the cscript engine. As written it echoes output to the console. To write the reversed lines to a file, use the > redirection operator like this

cscript //nologo revfile.vbs "input.txt" > "output.txt"

Use quotes around the file names/paths if they have spaces.

C:Test>type input.txt

apple

bear

cat

dog

egg

fog

gas

hip



ink

joe

kilo



C:Test>type output.txt

kilo

joe

ink



hip

gas

fog

egg

dog

cat

bear

apple