Redirect Windows cmd stdout and stderr to a single file

Question

I m trying to redirect all output  stdout   stderr  of a DOS command to a single file   C   gt dir 1 gt  a txt 2 gt  a txt The process cannot access the file because it is being used by another process    Is it possible  or should I just redirect to two separate files

User · Answer

Anders Lindahl s answer is correct  but it should be noted that if you are redirecting stdout to a file and want to redirect stderr as well then you MUST ensure that 2 gt  amp 1 is specified AFTER the 1 gt  redirect  otherwise it will not work   REM     WARNING  THIS WILL NOT REDIRECT STDERR TO STDOUT      dir 2 gt  amp 1  gt  a txt

User · Answer

Background info from MSKB  While the accepted answer to this question is correct  it really doesn t do much to explain why it works  and since the syntax is not immediately clear I did a quick google to find out what was actually going on   In the hopes that this information is helpful to others  I m posting it here   Taken from MS Support KB 110930      From MSKB110930     Redirecting Error Messages from Command Prompt  STDERR STDOUT      Summary      When redirecting output from an application using the     symbol  error messages still print to the screen  This is because error messages are often sent to the Standard Error stream instead of the Standard Out stream       Output from a console  Command Prompt  application or command is often sent to two separate streams  The regular output is sent to Standard Out  STDOUT  and the error messages are sent to Standard Error  STDERR   When you redirect console output using the     symbol  you are only redirecting STDOUT  In order to redirect STDERR you have to specify  2   for the redirection symbol  This selects the second output stream which is STDERR       Example      The command dir file xxx  where file xxx does not exist  will display the following output   Volume in drive F is Candy Cane Volume Serial Number is 34EC-0876  File Not Found       If you redirect the output to the NUL device using dir file xxx  gt  nul  you will still see the error message part of the output  like this   File Not Found       To redirect  only  the error message to NUL  use the following command   dir file xxx 2 gt  nul       Or  you can redirect the output to one place  and the errors to another   dir file xxx  gt  output msg 2 gt  output err       You can print the errors and standard output to a single file by using the   amp 1  command to redirect the output for STDERR to STDOUT and then sending the output from STDOUT to a file   dir file xxx 1 gt  output msg 2 gt  amp 1

User · Answer

Correct  file handle 1 for the process is STDOUT  redirected by the 1 gt  or by  gt   1 can be omitted  by convention  the command interpreter  cmd exe  knows to handle that   File handle 2 is STDERR  redirected by 2 gt    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 redirected will overwrite  replace  the previous log file   The  gt  gt   for either STDOUT or STDERR  will APPEND not REPLACE the file  So you get a cumulative logfile  showwing the results from all runs of the process - typically more useful   Happy trails

User · Answer

There is  however  no guarantee that the output of SDTOUT and STDERR are interweaved line-by-line in timely order  using the POSIX redirect merge syntax   If an application uses buffered output  it may happen that the text of one stream is inserted in the other at a buffer boundary  which may appear in the middle of a text line   A dedicated console output logger  I e  the  StdOut StdErr Logger  by  LoRd MuldeR   may be more reliable for such a task   See  MuldeR s OpenSource Projects

User · Answer

To add the stdout and stderr to the general logfile of a script   dir  gt  gt  a txt 2 gt  amp 1

User · Answer

In a batch file  Windows 7 and above  I found this method most reliable  Call  logging  gt  C  Temp NAME Your Log File txt  2 gt  amp 1  logging TITLE  Logging Commands  ECHO  Read this output in your log file  ECHO    Prompt    COLOR 0F   Obviously  use whatever commands you want and the output will be directed to the text file  Using this method is reliable HOWEVER there is NO output on the screen

User · Answer

You want   dir  gt  a txt 2 gt  amp 1   The syntax 2 gt  amp 1 will redirect 2  stderr  to 1  stdout   You can also hide messages by redirecting to NUL  more explanation and examples on MSDN

[windows] Redirect Windows cmd stdout and stderr to a single file

Examples related to windows

Examples related to command-line

Examples related to cmd

Examples related to pipe