console) if not explicitly specified. Escaping Redirection (not to be interpreted as "Avoiding Redirection") Redirection always uses the main or first command's streams: START command > logfile will redirect START's Standard Output to logfile, not command's! up vote 1 down vote You want command > null 2>&1 nul only works in command prompt whereas null works in powershell Null can be used in and cmd.exe for compatibility SomeCommand.exe > temp.txt OtherCommand.exe >> temp.txt By default, the > and >> operators redirect stdout. have a peek at this web-site
Happy trails... 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 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 That's because >NUL redirects all Standard Output to the NUL device, which does nothing but discard it. http://www.robvanderwoude.com/battech_redirection.php
But are the semantic rules documented anywhere because I reckon this is something worthwhile to learn as it could waste hours. –igbgotiz Jul 14 '14 at 22:09 7 @igbgotiz 2>&1 CMD Syntax TYPE - Display the contents of one or more text files Q245031 - Error when using the | pipe symbol Successive redirections explained (1>&3 ) - Stack Overflow Equivalent 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
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 Not the answer you're looking for? Use >CON to send text to the screen, no matter what, even if the batch file's output is redirected. Windows Redirect Stderr To Null Learning the correct way to escape characters in command is a much better idea. –DavidPostill Jul 27 at 12:46 Please teach me how to escape attaching output using >>.
What 2>&1 does, is merge Standard Error into the Standard Output stream, so Standard output and Standard Error will continue as a single stream. Windows Redirect Stderr To Stdout Does a long flight on a jet provide a headstart to altitude acclimatisation? Hi, I'm Steve. http://stackoverflow.com/questions/1420965/redirect-stdout-and-stderr-to-a-single-file 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
We'll see how we can use this later. Windows Tee Output 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). This could be useful when prompting for input even if the batch file's output is being redirected to a file. 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
To illustrate my story there are some examples you can try for yourself. http://www.robvanderwoude.com/redirection.php Sending a stranger's CV to HR Achieve same random number sequence on different OS with same seed Will I encounter any problems as a recognizable Jew in India? Windows Command Line Redirect Output To File And Screen 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. Windows Stderr However, I am pretty sure it is just my faulty memory because I was on Windows at the time. –Alec Gorge Aug 18 '10 at 3:15 add a comment| 2 Answers
There are tricks to decrease the number of file handles lost by redirection: redirect to (one single temporary) file instead of NUL specify a directory if you have to redirect to Use >CON to send text to the screen, no matter what, even if the batch file's output is redirected. Redirection from a device is not always possible. (2) Redirection to the NUL device is often used to hide standard output, instead of displaying it on screen: COPY *.* A: Source Not the answer you're looking for?
Use >logfile.txt2>errorlog.txt to redirect success and error messages to separate log files. Windows Echo To Stderr thanks! –wasatchwizard Apr 4 '13 at 17:55 1 @wasatchwizard Ithink I had trouble with that, but >NUL 2>NUL worked fine –FrinkTheBrave Aug 4 '14 at 8:24 4 If there Try this command: ECHO Hello world 2>NUL What you should get is: Hello world You see?
A workaround that may look a bit intimidating is grouping the command line and escaping the redirection: START CMD.EXE /C ^(command ^> logfile^) What this does is turn the part between Those of you familiar with one of the Unix/Linux shells probably know what these streams are: Standard Output Standard Error Console Standard Output is the stream where all, well, standard output Duly edited my answer. –AirCombat Jul 29 '15 at 18:54 add a comment| Your Answer draft saved draft discarded Sign up or log in Sign up using Google Sign up Batch File Output To Text File Append more stack exchange communities company blog Stack Exchange Inbox Reputation and Badges sign up log in tour help Tour Start here for a quick overview of the site Help Center Detailed
Make sure you place the redirection "commands" in this order. Thank you! –Nam G VU Dec 20 '13 at 7:10 1 Is it explaned anywhere why putting 2>&1 before 1> will not achieved the intended effect? We’ll sort the output of the DIR commmand. And, no, I'm not Steve Jansen the British jazz drummer, though that does sound like a sweet career.
With the NUL device that's no problem, but when redirecting to a file one of the redirections will lock the file for the other redirection. Is there any way to bring an egg to its natural state (not boiled) after you cook it? Display text To display a text on screen we have the ECHO command: ECHO Hello world This will show the following text on screen: Hello world When I say "on screen", 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
How to defeat the elven insects using modern technology? That's because we redirected the Standard Error stream to the NUL device, but the ECHO command sent its output to the Standard Output stream, which was not redirected. A CMD error is an error raised by the command processor itself rather than the program/command. Note however, that a space between an ECHO command and a > will be redirected too.
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