How to reverse text file in Windows

Question

Please help me, how reverse/sort row in text file with batch in Windows?
Example:
I have text in this format

15/04/2013-07:10:30 lalala
15/04/2013-07:10:30 Text text
15/04/2013-07:10:30 1 lala Text

15/04/2013-07:10:36 8 text lala X
15/04/2013-07:10:36 A text lala 1

17/04/2013-10:11:12 B bext lala 4
... (other rows)

and I need reversed it in this format

17/04/2013-10:11:12 B bext lala 4
15/04/2013-07:10:36 A text lala 1
15/04/2013-07:10:36 8 text lala X
15/04/2013-07:10:30 1 lala Text
15/04/2013-07:10:30 Text text
15/04/2013-07:10:30 lalala
... (other rows)

Thank You for Your help!

score 13 · Answer 1 · answered Apr 15 '13 at 11:33

~~Maybe it's not the prettiest way, but it's just simple and works as you want.~~

echo. > output.txt

for /f  "delims=@" %%j in (yourfile.txt) do (
    type output.txt > tmp
    echo %%j > output.txt
    type tmp >> output.txt
)

del tmp

Don't use the example above if you want to process large files. It's really time and resources consuming solution. Here you have faster version I just prepared:

setlocal enabledelayedexpansion

set I=0

for /F "tokens=*" %%k in (yourfile.txt) do (
  set /A I=!I! + 1
  set LINE!I!=%%k
)

for /L %%c in (!I!,-1,1) do (
  echo !LINE%%c! >> out.txt
)

Reversing 40kb file (10k lines, 1 character in each) took ~1 minute on my machine. Remember it's still only batch. There are many better scripting or programming languages that would be better to perform that operation.

score 3 · Answer 2 · edited Jun 26 '17 at 06:38

3

perl -e "print reverse <>" file > file_reversed

Note that on Windows you will have to use double quotes instead of single quotes to delimit the perl string.

edited Jun 26 '17 at 06:38

Matthew Lock

4,757

answered Jan 20 '17 at 11:02

Kjetil S.

609

score 1 · Answer 3 · answered Apr 15 '13 at 14:11

I thought I would add this as a second approach, as it might work better for some:

If you are open to something you can call, instead of batch logic:

This is a .NET application that you drop to %Systemroot% and call just like any other command in a batch, .bat, .cmd etc.1

Usage looks like: Reverse "C:\Path\File.txt" enter image description here

And, yes, I own the thing. It seems easier to me to call this than write the logic out. It will replace the file contents, at present at least and not create a second file.

score 1 · Answer 4 · edited May 30 '13 at 17:59

1

sort /r yourfile.txt > out.txt

This will put out all lines in yourfile.txt in reverse alphabetical order. Note that this may differ from putting out all lines in yourfile.txt in actual reverse order.

edited May 30 '13 at 17:59

C.O.

103

answered Apr 26 '13 at 23:33

VeggieVampire

27
2

score -1 · Answer 5 · edited Dec 07 '16 at 18:39

exactly 10 lines perl, taking into account that nothing will be done if output file already exists:

#!/usr/bin/perl
usage() if( !$ARGV[0] );
my $f_out = my $f_in = $ARGV[0];
$f_out =~ s/(\..{1,3})?$/.reverse$1/i;
open(TXTIN, "<$f_in") || usage("Can't read file [$f_in]");
my @in = <TXTIN>; close(TXTIN);
usage( "File already exists, nothing done [$f_out]" ) if( -e $f_out );
open(TXTOUT, ">$f_out"); print TXTOUT join( '', reverse( @in ) ); close(TXTOUT);
print "File reverse written [$f_out]\n";
sub usage { print "$_[0]\nUsage: [perl] rev2.pl (filename)\n"; exit; }

How to reverse text file in Windows

5 Answers5

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