Displaying Windows command prompt output and redirecting it to a file

There's a Win32 port of the Unix tee command, that does exactly that. See http://unxutils.sourceforge.net/ or http://getgnuwin32.sourceforge.net/

I was able to find a solution/workaround of redirecting output to a file and then to the console:

dir > a.txt | type a.txt

where dir is the command which output needs to be redirected, a.txt a file where to store output.

Unfortunately there is no such thing.

MS-DOS applications (and Windows console applications, too) only have a single output handle. (Well, there are two STDOUT, STDERR but it doesn't matter here) The > redirects the output normally written to the console handle to a file handle.

If you want to have some kind of multiplexing you have to use an external application which you can divert the output to. This application then can write to a file and to the console again.

A simple C# console application would do the trick:

using System;
using System.Collections.Generic;
using System.IO;

namespace CopyToFiles
{
    class Program
    {
        static void Main(string[] args)
        {
            var buffer = new char[100];
            var outputs = new List<TextWriter>();

            foreach (var file in args)
                outputs.Add(new StreamWriter(file));

            outputs.Add(Console.Out);

            int bytesRead;
            do
            {
                bytesRead = Console.In.ReadBlock(buffer, 0, buffer.Length);
                outputs.ForEach(o => o.Write(buffer, 0, bytesRead));
            } while (bytesRead == buffer.Length);

            outputs.ForEach(o => o.Close());
        }
    }
}

To use this you just pipe the source command into the program and provide the path of any files you want to duplicate the output to. For example:

dir | CopyToFiles files1.txt files2.txt

Will display the results of dir as well as store the results in both files1.txt and files2.txt.

Note that there isn't much (anything!) in the way of error handling above, and supporting multiple files may not actually be required.

I agree with Brian Rasmussen, the unxutils port is the easiest way to do this. In the Batch Files section of his Scripting Pages Rob van der Woude provides a wealth of information on the use MS-DOS and CMD commands. I thought he might have a native solution to your problem and after digging around there I found TEE.BAT, which appears to be just that, an MS-DOS batch language implementation of tee. It is a pretty complex-looking batch file and my inclination would still be to use the unxutils port.

tori3852

I found that

dir > a.txt | type a.txt

didn't work (first few lines of dir listing only - suspect some sort of process forking and the second part, the 'type' command terminated before the dire listing had completed? ), so instead I used:-

dir > z.txt && type z.txt

which did - sequential commands, one completes before the second starts. Thanks. Good to find this stuff, appreciated.

mtee is a small utility which works very well for this purpose. It's free, source is open, and it Just Works.

You can find it at http://www.commandline.co.uk.

Used in a batch file to display output AND create a log file simultaneously, the syntax looks like this:

    someprocess | mtee /+ mylogfile.txt

Where /+ means to append output.

This assumes that you have copied mtee into a folder which is in the PATH, of course.

Here's a sample of what I've used based on one of the other answers

@echo off
REM SOME CODE
set __ERROR_LOG=c:\errors.txt
REM set __IPADDRESS=x.x.x.x

REM Test a variable
if not defined __IPADDRESS (
     REM Call function with some data and terminate
     call :TEE %DATE%,%TIME%,IP ADDRESS IS NOT DEFINED
     goto :EOF
)

REM If test happens to be successful, TEE out a message and end script.
call :TEE Script Ended Successful
goto :EOF


REM THE TEE FUNCTION
:TEE
for /f "tokens=*" %%Z in ("%*") do (
     >  CON ECHO.%%Z
     >> "%__ERROR_LOG%" ECHO.%%Z
     goto :EOF
)

@echo on

set startDate=%date%
set startTime=%time%

set /a sth=%startTime:~0,2%
set /a stm=1%startTime:~3,2% - 100
set /a sts=1%startTime:~6,2% - 100


fullprocess.bat > C:\LOGS\%startDate%_%sth%.%stm%.%sts%.LOG | fullprocess.bat

This will create a log file with the current datetime and you can the console lines during the process

Following helps if you want something really seen on the screen - even if the batch file was redirected to a file. The device CON maybe used also if redirected to a file

Example:

ECHO first line on normal stdout. maybe redirected
ECHO second line on normal stdout again. maybe redirected
ECHO third line is to ask the user. not redirected  >CON
ECHO fourth line on normal stdout again. maybe redirected

Also see good redirection description: http://www.p-dd.com/chapter7-page14.html

How do I display and redirect output to a file. Suppose if I use dos command, dir > test.txt ,this command will redirect output to file test.txt without displaying the results. how to write a command to display the output and redirect output to a file using DOS i.e., windows command prompt, not in UNIX/LINUX.

You may find these commands in biterscripting ( http://www.biterscripting.com ) useful.

var str output
lf > $output
echo $output                            # Will show output on screen.
echo $output > "test.txt"               # Will write output to file test.txt.
system start "test.txt"                 # Will open file test.txt for viewing/editing.

This works, though it's a bit ugly:

dir >_ && type _ && type _ > a.txt

It's a little more flexible than some of the other solutions, in that it works statement-by-statement so you can use it to append as well. I use this quite a bit in batch files to log and display messages:

ECHO Print line to screen and log to file.  >_ && type _ && type _ >> logfile.txt

Yes, you could just repeat the ECHO statement (once for the screen and the second time redirecting to the logfile), but that looks just as bad and is a bit of a maintenance issue. At least this way you don't have to make changes to messages in two places.

Note that _ is just a short filename, so you'll need to make sure to delete it at the end of your batch file (if you're using a batch file).

dir 1>a.txt 2>&1 | type a.txt

This will help to redirect both STDOUT and STDERR

Check this out: wintee

No need for cygwin.

I did encounter and report some issues though.

This works in real time but is also kind a ugly and the performance is slow. Not well tested either:

@echo off
cls
SET MYCOMMAND=dir /B
ECHO File called 'test.bat' > out.txt
for /f "usebackq delims=" %%I in (`%MYCOMMAND%`) do (
  ECHO %%I
  ECHO %%I >> out.txt
) 
pause

An alternative is to tee stdout to stderr within your program:

in java:

System.setOut(new PrintStream(new TeeOutputStream(System.out, System.err)));

Then, in your dos batchfile: java program > log.txt

The stdout will go to the logfile and the stderr (same data) will show on the console.