Output from a console (Command Prompt) application or command is often sent to two separate streams. The batch file would look like this: command > logfile and the command line would be: START batchfile Some "best practices" when using redirection in batch files: Use >filename.txt 2>&1 to That's because >NUL redirects all Standard Output to the NUL device, which does nothing but discard it. It can just be dir >> a.txt 2>&1 –raychi Sep 11 '15 at 23:06 add a comment| up vote 4 down vote I just chopped out the answer as @Anders just have a peek here
Why did my cron job run? Try our newsletter Sign up for our newsletter and get our top new questions delivered to your inbox (see an example). Note that if you're using these to make log files, then unless you're sending the outut to _uniquely_named_ (eg date-and-time-stamped) log files, then if you run the same process twice, the So the interpretation of the parenthesis and redirection is delayed, or deferred. http://www.robvanderwoude.com/battech_redirection.php
In this case, we could also have used test.bat>NUL2>NUL This redirects Standard Output to the NUL device and Standard Error to the same NUL device. Why did the snake only speak to Chava? Use 1>&2 to send text to Standard Error. By definition Console isn't a stream.
In Windows XP the result is no text on screen and file.txt containing the line Helloworld2, including the trailing "2" (CMD.EXE interprets it as ECHOHelloworld2>file.txt). Take a look at some of the examples available, they will give you an impression of the many possibilities of redirection page last uploaded: 2016-09-19, 14:57 ( SS64 ) CMD Syntax Some notes on this subject can be found on my Temporary Files page. Windows Redirect Stderr To Null Are there textual deviations between the Dead Sea Scrolls and the Old Testament?
I strongly suspect this has got to do with the way "cmd" parses commands that gives two different meanings depending on the order in which you specify the redirection. The “Standard Out” file, known as stdout, is used to write output for display on the screen. The escape characters themselves will not be visible in the ECHOed line, so the temporary batch file will contain the normal, unescaped pipe and redirection symbol again. http://stackoverflow.com/questions/1420965/redirect-stdout-and-stderr-to-a-single-file ECHO I suppose that's why CTTY is no longer available on Windows systems.
Where will the second Fantastic Beasts film be set? Windows Tee Output The command interpreter first creates the empty destination file, then runs the DIR command and finally saves the redirected text into the file. I have used the following to send all output to a file, but again I don't want any file output: command > out.txt 2>&1 I have used command > /dev/null on Note: Be careful when using workarounds like these, they may be broken in future (or even past) Windows versions.
What does "M.C." in "M.C. DIR>filename.txt and DIR>filename.txt are identical, ECHOHelloworld>filename.txt and ECHOHelloworld>filename.txt are not, even though they are both valid. Windows Command Line Redirect Output To File And Screen Browse other questions tagged command-line batch redirection or ask your own question. Windows Stderr Display & Redirect Output On this page I'll try to explain how redirection works.
Use >CON to send text to the screen, no matter what, even if the batch file's output is redirected. navigate here In most cases the Exit Code is the same as the ErrorLevel Numeric handles: STDIN = 0 Keyboard input STDOUT = 1 Text output STDERR = 2 Error text output UNDEFINED Given that ice is less dense than water, why doesn't it sit completely atop water (rather than slightly submerged)? I can assure you I did try! Batch File Redirect Output To File
Now try this (note the typo): EHCO Hello world>NUL The result may differ for different operating system versions, but in Windows XP I get the following error message: 'EHCO' is not The batch file would look like this: command > logfile and the command line would be: START batchfile Some "best practices" when using redirection in batch files: Use >filename.txt 2>&1 to What is an instant of time? Check This Out To prevent this ambiguity, either use parentheses or insert an extra space yourself: ECHO Hello World2 >file.txt
(ECHO Hello World2)>file.txt "Merging" Standard Output and Standard Error with 2>&1 can also
Then, after both of them are already joined together, you're redirecting stdout (> with no specifier) to the file. Windows Echo To Stderr REM *** WARNING: THIS WILL NOT REDIRECT STDERR TO STDOUT **** dir 2>&1 > a.txt share|improve this answer edited Oct 9 '15 at 19:40 Peter Mortensen 10.3k1369107 answered May 23 '13 And some, not many, commands send their output to the screen bypassing Standard Output and Standard Error, they use the Console.
We’ll sort the output of the DIR commmand. Try this command: ECHO Hello world 2>NUL What you should get is: Hello world You see? In Windows NT4 and later (CMD.EXE) and in OS/2 (also CMD.EXE) Standard Error can be redirected by using 2> instead of > A short demonstration. Batch File Output To Text File Append But the next one is new: test.bat > NUL 2>&1 and you should see: C:\>test.bat This text goes to the Console C:\>_ This time we redirected both Standard Output and Standard
This file now contains the stdout and stderr output of your command. Probably the most familiar example is MORE: DIR /S | MORE where the MORE command accepts DIR's Standard Output at its own Standard Input, chops the stream in blocks of 25 Why is the FBI making such a big deal out Hillary Clinton's private email server? http://introbuilder.net/batch-file/windows-batch-error-output-redirect.php For example, this syntax works, but would fail if the second or subsequent (piped) lines were indented with a space: @Echo Off echo abc def |^ find "abc" |^ find "def">
To get rid of screen output sent directly to the Console, either run the program in a separate window (using the START command), or clear the screen immediately afterwards (CLS). that works. Since DOS treats devices like AUX, COMn, LPTn, NUL and PRN as files, opening a device will claim one file handle. Not the answer you're looking for?
Take this imaginary batch file, for example: ECHO Directory of all files on C: >> LOG1.LOG
DIR C:\ /S >> LOG1.LOG Not exactly easy on the eye, that one? Smythe Jul 29 '15 at 16:43 I had no idea. This is a fine demonstration of only Standard Output being redirected to the NUL device, but Standard Error still being displayed. console) if not explicitly specified.
You may say 'It worked!', if you want. Please click the link in the confirmation email to activate your subscription. From my Windows help, I searched on redirection (URL ms-its:C:\WINDOWS\Help\ntcmds.chm::/redirection.htm). Is it possible, or should I just redirect to two separate files?
Make sure you place the redirection "commands" in this order. Besides being used for redirection to the NUL device, with CTTYCOM1 the control could be passed on to a terminal on serial port COM1. Nothing That's because the error message was sent to the Standard Error stream, which was in turn redirected to the NUL device by 2>NUL When we use > to redirect Standard Nothing new so far.
This will only work in OS/2 and NT, not in MS-DOS.