Hidden features of Windows batch files

Question

What are some of the lesser know  but important and useful features of Windows batch files   Guidelines    One feature per answer Give both a short description of the feature and an example  not just a link to documentation Limit answers to native funtionality  i e   does not require additional software  like the Windows Resource Kit   Clarification  We refer here to scripts that are processed by cmd exe  which is the default on WinNT variants    See also  Windows batch files   bat vs  cmd

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A very old  ca 1990  trick to get the total size of the environment variables   set  gt  test dir test del test

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HELP   When working with different OS version it s important to know what commands are available natively   Typing HELP at the command prompt shows what commands are available  with a brief description of what they do   cmd exe       This will list all the command line parameters for launching a command prompt as well as registry tweaks that change system wide behavior

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The FOR command   While I hate writing batch files  I m thankful for it   FOR  F  eol   tokens 2 3  delims      i in  myfile txt  do  echo  i  j  k   would parse each line in myfile txt  ignoring lines that begin with a semicolon  passing the 2nd and 3rd token from each line to the for body  with tokens delimited by commas and or spaces  Notice the for body statements reference  i to get the 2nd token   j to get the 3rd token  and  k to get all remaining tokens after the 3rd   You can also use this to iterate over directories  directory contents  etc

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TheSoftwareJedi already mentioned the for command  but I m going to mention it again as it is very powerful   The following outputs the current date in the format YYYYMMDD  I use this when generating directories for backups   for  f  tokens 2-4 delims  -    a in   DATE T   do echo  c b a

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Subroutines  outputs 42         echo off     call  answer 42     goto  eof  do something     echo  1     goto  eof   and subroutines returning a value  outputs 0  1  2  and so on         echo off     setlocal enableextensions enabledelayedexpansion     call  seq init seq1  loop1     if not  seq1    10           call  seq next seq1         echo  seq1          goto  loop1           endlocal     goto  eof   seq init     set  a   1   -1      goto  eof  seq next     set  a  seq next tmp1    1      set  a   1    seq next tmp1    1      set seq next tmp1      goto  eof

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Rather than litter a script with REM or    lines  I do the following at the top of each script    echo OFF goto  START  Description of the script   Usage     myscript -parm1 parm2  gt  result txt   START   Note how you can use the pipe and redirection characters without escaping them

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Here how to build a CLASSPATH by scanning a given directory   setlocal ENABLEDELAYEDEXPANSION if defined CLASSPATH  set CLASSPATH  CLASSPATH     else  set CLASSPATH    FOR  R   lib   G IN    jar  DO set CLASSPATH  CLASSPATH    G Echo The Classpath definition is  CLASSPATH    works in XP  or better   With W2K  you need to use a couple of BAT files to achieve the same result  see Include all jars in the classpath definition     It s not needed for 1 6 since you can specify a wildcard directly in CLASSPATH  ex  -cp    lib

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Setting environment variables from a file with SET  P  SET  P SVNVERSION  lt ver tmp

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Redirecting output to the console  even if the batch s output is already redirected to a file via the  gt  con syntax   Example  foo cmd   echo a echo b  gt  con   Calling   foo cmd  gt  output txt   This will result in  a  going to output txt yet  b  going to the console

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The subdirectory option on  remove directory    rd  s  q junk

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Findstr with regular expression support   findstr    0-9     c  windows system32 drivers etc hosts

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Multiple commands in one line  useful in many situations    amp    Used to combine two commands  executes command1 and then command2  amp  amp   A conditional combination  executes command2 if command1 completes successfully       Command2 executes only if command1 does not complete successfully   Examples         Edit the most recent  TXT file and exit  useful in a  CMD    BAT    FOR  F   I IN   DIR   TXT  B  O -N   DO NOTEPAD   I  amp  EXIT         If exist any  TXT file  display the list in NOTEPAD  if not it        exits without any error  note the  amp  amp  and the 2 gt  error redirection  DIR   TXT  gt  TXT LST 2 gt  NUL  amp  amp  NOTEPAD TXT LST

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Doesn t provide much functionality  but you can use the title command for a couple of uses  like providing status on a long script in the task bar  or just to enhance user feedback    title Searching for        processing search  title preparing search results    data processing

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To set an enivroment variable from the first line of a file  I use this   rem a txt contains one line  abc123 set  p DATA  lt a txt echo data   DATA    This will output  abc123

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SHIFT   It s a way to iterate through a variable number of arguments passed into a script  or sub-routine  on the command line   In its simplest usage  it shifts  2 to be  1   3 to be  2  and so-on    You can also pass in a parameter to SHIFT to skip multiple arguments    This makes the command  destructive   i e   1 goes away forever   but it allows you to avoid hard-coding a maximum number of supported arguments   Here s a short example to process command-line arguments one at a time    ParseArgs  if   1            goto  DoneParsingArgs    rem     do something with  1      shift  goto  ParseArgs    DoneParsingArgs  rem

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I find the ease with which you can redirect the output of commands to files extremely useful   DIR   txt  gt  tmp txt DIR   exe  gt  gt  tmp txt   Single arrow creates  or overwrites the file  double arrow appends to it   Now I can open tmp txt in my text editor and do all kinds of good stuff

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Command separators   cls  amp  dir copy a b  amp  amp  echo Success copy a b    echo Failure   At the 2nd line  the command after  amp  amp  only runs if the first command is successful   At the 3rd line  the command after    only runs if the first command failed

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Creating an empty file    gt  copy nul filename ext

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To hide all output from a command redirect to  nul 2  amp 1   For example  the some command line programs display output even if you redirect to  nul  But  if you redirect the output like the line below  all the output will be suppressed   PSKILL NOTEPAD  gt nul 2 gt  amp 1   EDIT  See Ignoring the output of a command for an explanation of how this works

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Create and start editing a new file  copy con new txt This is the contents of my file  Z   Ctrl Z sends the ASCII EOF character  This is like heredocs in bash   cat  lt  lt EOF  gt  new txt This is the contents of my file EOF

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A very old  ca 1990  trick to get the total size of the environment variables   set  gt  test dir test del test

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With regard to using    instead of REM for comments  be careful     is a special case of a CALL label that acts like a comment  When used inside brackets  for instance in a FOR or IF loop  the function will prematurely exit  Very frustrating to debug    See http   www ss64 com nt rem html for a full description    adding as a new answer instead of a comment to the first mention of this above because I m not worthy of commeting yet  0

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I really like this Windows XP Commands reference  as well as the Syntax link at the top  it covers many of the tips and tricks already found in other answers

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For loops with numeric counters  outputs 1 through 10    for  l  i in  1 1 10  do echo  i

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Command separators   cls  amp  dir copy a b  amp  amp  echo Success copy a b    echo Failure   At the 2nd line  the command after  amp  amp  only runs if the first command is successful   At the 3rd line  the command after    only runs if the first command failed

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There is also the EDLIN command  While it may be an old bastard tool once used for line-based text editing  the fact that it s controllable from the command line makes it rather useful for batch scripting  mostly because  just like any other case you d be using EDLIN  it s the only tool available  After all  EDLIN is not a tool you would ordinarily want to use for text editing  unless you are somewhat masochistic  To quote Tim Patterson  the fellow who wrote it    I was aghast when I heard that IBM was using it and not throwing it out the window    NOTE  EDLIN adds old-fashioned EOF  1A  markers to files it edits  If you need to remove them  you ll probably have to use DEBUG

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Searching for an executable on the path  or other path-like string if necessary    c   gt  for  i in  cmd exe  do  echo     PATH i C  WINDOWS system32 cmd exe  c   gt  for  i in  python exe  do  echo     PATH i C  Python25 python exe  c   gt

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Integer arithmetic    gt  SET  A result 10 3   1 4

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For parsing stdin from inside a script you need that trick with the FOR and FIND commands   for  f  tokens      g in   find  V      do           do what you want with   g      echo   g

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Append files using copy   copy file1 txt file2 txt file3 txt append txt   Also  to set all CLI parameters to a single variable   SET MSG      This will take every word  or symbol  that is separated by spaces and save it to a single batch file variable  Technically  each parameter is  1   2   3  etc   but this SET command uses a wildcard to reference every parameter in stdin   Batch File    SET MSG     echo  MSG    Command Line   C  test gt test bat Hello World  Hello World

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the correct format for loops with numeric variables is  for  l   i in  startNumber  counter  endNumber  do echo   i   more details   http   www ss64 com nt for html

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This batch file works both with simple files as well as directories as command line parameters  you can mix them in any order   The loop runs the command   echo  in this example  on any specified file  if a parameter is a directory it runs the command recursively on each file in it    echo off for  f  delims     f in   dir     a-d  b  s   do echo   f

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Creating an empty file    gt  copy nul filename ext

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One of the most common requirements of batch scripting is to log the output generated for later review  Yes  you can redirect the stdout and stderr to a file but then you can t see what is going on unless you tail the log file   So consider running  your batch scripts using a stdout stderr logging utility like logger which will log the output with a timestamp and you are still able to see the script progress as it happens   Yet another stdout stderr logging utility  Yet another stdout stderr logging utility  2010-08-05  Copyright  C  2010 LoRd MuldeR  lt MuldeR2 GMX de gt  Released under the terms of the GNU General Public License  see License txt   Usage    logger exe  logger options    program exe  program arguments    program exe  program arguments    logger exe  logger options    -  Options    -log  lt file name gt   Name of the log file to create  default    lt program gt   lt time gt  log     -append           Append to the log file instead of replacing the existing file   -mode  lt mode gt       Write  stdout  or  stderr  or  both  to log file  default   both     -format  lt format gt   Format of log file   raw  or  time  or  full   default   time     -filter  lt filter gt   Don t write lines to log file that contain this string   -invert           Invert filter  i e  write only lines to log file that match filter   -ignorecase       Apply filter in a case-insensitive way  default  case-sensitive    -nojobctrl        Don t add child process to job object  applies to Win2k and later    -noescape         Don t escape double quotes when forwarding command-line arguments   -silent           Don t print additional information to the console   -priority  lt flag gt   Change process priority  idle belownormal normal abovenormal high    -inputcp  lt cpid gt    Use the specified codepage for input processing  default   utf8     -outputcp  lt cpid gt   Use the specified codepage for log file output  default   utf8

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Variable substrings    gt  set str 0123456789  gt  echo  str  0 5  01234  gt  echo  str  -5 5  56789  gt  echo  str  3 -3  3456

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To quickly convert an Unicode text file  16bit char  to a ASCII DOS file  8bit char    C   gt  type unicodeencoded txt  gt  dosencoded txt   as a bonus  if possible  characters are correctly mapped

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Line continuation   call C  WINDOWS system32 ntbackup exe       backup        V yes        R no        RS no        HC off        M normal        L s        daily bks        F daily bkf

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HELP   When working with different OS version it s important to know what commands are available natively   Typing HELP at the command prompt shows what commands are available  with a brief description of what they do   cmd exe       This will list all the command line parameters for launching a command prompt as well as registry tweaks that change system wide behavior

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The goto  eof pasteboard  I add  goto  eof  to end of my scripts as a handy space for code fragments  That way I can quickly copy paste to and from this area  without having to comment uncomment   goto  eof    code scraps call this bat call that bat set TS  DATE  10  DATE  4 2  DATE  7 2 - TIME  0 2  TIME  3 2  TIME  6   for  R C  temp    G in    bak  DO del   G

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Using pushd to a UNC path will create a temporary drive mapping  starting with Z and working backward to find the next available letter  and put you in that drive and path  When you popd or exit the command prompt  the temporary mapping is gone      C   gt pushd   yourmom jukebox     Z   gt pushd   yourmom business     Y   gt    Also  not so much a batch tip as a command-line environment tip  but when you re working at the commandline with pushd and popd and network shares  it s useful to modify your prompt with the     show pushd stack depth  and  M  show network share path       C  utils gt prompt    m p g     C  utils gt pushd m         yourmom pub M   gt pushd c         c   gt pushd    M      C  utils         c   gt popd        yourmom pub M   gt popd     C  utils gt

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Arrays in batch-files   Set a value   set count 1 set var count  42   Extract a value at the command-line   call echo  var count     Extract a value in a batch-file   call echo   var count      Note the extra strafing   signs   The technique may look a little hairy  but it s quite useful  The above will print the contents of var1  i e  42  as we explained  We could also replace the echo command with a set if we wanted to set some other variable to the value in var1  Meaning the following is a valid assignment at the command line   call set x  var count     Then to see the value of va1   echo  x

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Quick edit mode in cmd exe is my favorite   This is slightly off topic  but when interacting with the command shell it can be a lifesaver   No  I m not being hyperbolic--you will only see caret-capitol-v a certain number of times before you die  the more you see  the faster you die    Open up regedit  caution  not my fault  blue screen  etc  Go to HKCU Console Set QuickEdit to 1    You can set this from the UI as well  which is probably the better way   See the comments for instructions   Also there s a nice one line script to do this as well    Now  to copy  just left-click and drag to select and right click to copy   To paste  just right click     NO MORE  V V V V V V V V V V V V V V      Crap  I think I just killed somebody   Sorry

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Subroutines  outputs 42         echo off     call  answer 42     goto  eof  do something     echo  1     goto  eof   and subroutines returning a value  outputs 0  1  2  and so on         echo off     setlocal enableextensions enabledelayedexpansion     call  seq init seq1  loop1     if not  seq1    10           call  seq next seq1         echo  seq1          goto  loop1           endlocal     goto  eof   seq init     set  a   1   -1      goto  eof  seq next     set  a  seq next tmp1    1      set  a   1    seq next tmp1    1      set seq next tmp1      goto  eof

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Variable substrings    gt  set str 0123456789  gt  echo  str  0 5  01234  gt  echo  str  -5 5  56789  gt  echo  str  3 -3  3456

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Doesn t provide much functionality  but you can use the title command for a couple of uses  like providing status on a long script in the task bar  or just to enhance user feedback    title Searching for        processing search  title preparing search results    data processing

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To get the current date   time to use for log files  etc   I use this in my batch files   for  f  usebackq tokens 1 2 3 4 5 6 7 delims         a in   echo  DATE   TIME    do set NOW   d  b  c   e  f  g set LOG output  NOW  log

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if block structure   if   VS90COMNTOOLS           echo  Visual Studio 2008 is not installed   exit  b

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Delayed expansion of variables  with substrings thrown in for good measure         echo off     setlocal enableextensions enabledelayedexpansion     set full  u01 users pax  loop1     if not   full  -1                    set full2  full  -1  full2          set full  full   -1          goto  loop1           echo  full      endlocal

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For parsing stdin from inside a script you need that trick with the FOR and FIND commands   for  f  tokens      g in   find  V      do           do what you want with   g      echo   g

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A lot of people use GOTO  EOF these days to terminate their batch files  but you can also use EXIT  B for this purpose   The advantage behind using EXIT  B is that you can add an errorlevel after EXIT  B  and it will exit with that errorlevel

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A very old  ca 1990  trick to get the total size of the environment variables   set  gt  test dir test del test

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Output a blank line   echo

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PAUSE   Stops execution and displays the following prompt   Press any key to continue        Useful if you want to run a batch by double-clicking it in Windows Explorer and want to actually see the output rather than just a flash of the command window

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Hide input for an interactive batch script      echo off    echo hP1X500P PZBBBfh b  fXf-V   fPf f3 f1 5  u5 gt in com    set  p secret password  Enter password   lt nul    for  f  tokens      i in   in com   do  set secret password   i     del in com

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For what it s worth  this is quite a good online reference for Windows CMD or batch files   I learned a few things I didn t know from it

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The subdirectory option on  remove directory    rd  s  q junk

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For loops with numeric counters  outputs 1 through 10    for  l  i in  1 1 10  do echo  i

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Sneaky trick to wait N seconds  not part of cmd exe but isn t extra software since it comes with Windows   see the ping line   You need N 1 pings since the first ping goes out without a delay       echo  time      call  waitfor 5     echo  time      goto  eof  waitfor     setlocal     set  a  t    1   1       gt nul ping 127 0 0 1 -n  t      endlocal     goto  eof

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Bail on error   IF   errorlevel   NEQ  0       echo  ERROR   Something broke   Bailing out      exit  B 1

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The   dp0 piece was mentioned already  but there is actually more to it  the character s  after the   define the information that is extracted  No letter result in the return of the patch file name d - returns the drive letter p - returns the path s - returns the short path x - returns the file extension So if you execute the script test bat below from the c  Temp long dir name  folder    echo off echo  0 echo   d0 echo   p0 echo   dp0 echo   x0 echo   s0 echo   sp0   you get the following output   test c   Temp long dir name  c  Temp long dir name   bat c  Temp LONGDI 1 test bat  Temp LONGDI 1     And if a parameter is passed into your script as in test c  temp mysrc test cpp the same manipulations can be done with the  1 variable   But the result of the expansion of  0 depends on the location  At the  top level  of the batch it expands to the current batch filename  In a function  call   it expands to the function name    echo off echo  0 call  test goto  eof   test echo  0 echo   0 echo   n0   The output is  the batchfile is started with myBatch bat    myBatch bat  test  test myBatch

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Escaping the  plumbing    echo      lt    gt    amp

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PAUSE   Stops execution and displays the following prompt   Press any key to continue        Useful if you want to run a batch by double-clicking it in Windows Explorer and want to actually see the output rather than just a flash of the command window

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example of string subtraction on date and time to get file named  YYYY-MM-DD HH MM SS txt      echo test  gt    date  0 4 - date  5 2 - date  8 2   time  0 2   time  3 2   time  6 2  txt    I use color to indicate if my script end up successfully  failed  or need some input by changing color of text and background  It really helps when you have some machine in reach of your view but quite far away     color XY   where X and Y is hex value from 0 to F  where X - background  Y - text  when X   Y color will not change      color Z   changes text color to  Z  and sets black background   color 0  won t work   for names of colors call      color

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Not sure how useful this would be in a batch file  but it s a very convenient command to use in the command prompt   C  some directory gt  start     This will open up Windows Explorer in the  some directory  folder   I have found this a great time-saver

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Allows you to change directory based on environment variable without having to specify the     directive  If the variable specified does not exist then try the directory name    if defined  1  call cd     1     else  call cd  1

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Local variables are still parsed for the line that ENDLOCAL uses  This allows for tricks like   ENDLOCAL  amp  SET MYGLOBAL  SOMELOCAL   amp  SET MYOTHERGLOBAL  SOMEOTHERLOCAL    This is is a useful way to transmit results to the calling context  Specifically   SOMELOCAL  goes out of scope as soon as ENDLOCAL completes  but by then  SOMELOCAL  is already expanded  so the MYGLOBAL is assigned in the calling context with the local variable   For the same reason  if you decide to do   ENDLOCAL  amp  SET MYLOCAL  MYLOCAL    You ll discover your new MYLOCAL variable is actually now around as a regular environment variable instead of the localized variable you may have intended it to be

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To quickly convert an Unicode text file  16bit char  to a ASCII DOS file  8bit char    C   gt  type unicodeencoded txt  gt  dosencoded txt   as a bonus  if possible  characters are correctly mapped

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This batch file works both with simple files as well as directories as command line parameters  you can mix them in any order   The loop runs the command   echo  in this example  on any specified file  if a parameter is a directory it runs the command recursively on each file in it    echo off for  f  delims     f in   dir     a-d  b  s   do echo   f

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the correct format for loops with numeric variables is  for  l   i in  startNumber  counter  endNumber  do echo   i   more details   http   www ss64 com nt for html

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The   dp0 piece was mentioned already  but there is actually more to it  the character s  after the   define the information that is extracted  No letter result in the return of the patch file name d - returns the drive letter p - returns the path s - returns the short path x - returns the file extension So if you execute the script test bat below from the c  Temp long dir name  folder    echo off echo  0 echo   d0 echo   p0 echo   dp0 echo   x0 echo   s0 echo   sp0   you get the following output   test c   Temp long dir name  c  Temp long dir name   bat c  Temp LONGDI 1 test bat  Temp LONGDI 1     And if a parameter is passed into your script as in test c  temp mysrc test cpp the same manipulations can be done with the  1 variable   But the result of the expansion of  0 depends on the location  At the  top level  of the batch it expands to the current batch filename  In a function  call   it expands to the function name    echo off echo  0 call  test goto  eof   test echo  0 echo   0 echo   n0   The output is  the batchfile is started with myBatch bat    myBatch bat  test  test myBatch

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When using command extensions shell options in a script  it is HIGHLY suggested that you do the following trick at the beginning of your scripts   -- Information pasted from http   www ss64 com nt setlocal html     SETLOCAL will set an ERRORLEVEL if given an argument  It will be zero if one of the two valid arguments is given and one otherwise       You can use this in a batch file to determine if command extensions are available  using the following technique    VERIFY errors 2 gt nul SETLOCAL ENABLEEXTENSIONS IF ERRORLEVEL 1 echo Unable to enable extensions      This works because  VERIFY errors  sets ERRORLEVEL to 1 and then the SETLOCAL will fail to reset the ERRORLEVEL value if extensions are not available  e g  if the script is running under command com       If Command Extensions are permanently disabled then SETLOCAL ENABLEEXTENSIONS will not restore them

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Call Set - Expands Environment variables several levels deep   Found this at http   ss64 com nt call html advanced from answer to another SO question Batch file variables initialized in a for loop  set VarName Param set Param This  call set Answer    Varname    Echo  Answer    gives   set VarName Param set Param This call set Answer  Param  Echo This This

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Integer arithmetic    gt  SET  A result 10 3   1 4

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The equivalent of the bash  and other shells   echo -n Hello   or echo Hello  c   which outputs  Hello  without a trailing newline  A cmd hack to do this    lt nul set  p any-variable-name Hello   set  p is a way to prompt the user for input  It emits the given string and then waits   on the same line  i e   no CRLF   for the user to type a response    lt nul simply pipes an empty response to the set  p command  so the net result is the emitted prompt string   The variable used remains unchanged due to the empty reponse    Problems are  It s not possible to output a leading equal sign  and on Vista leading whitespace characters are removed  but not on XP

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The equivalent of the bash  and other shells   echo -n Hello   or echo Hello  c   which outputs  Hello  without a trailing newline  A cmd hack to do this    lt nul set  p any-variable-name Hello   set  p is a way to prompt the user for input  It emits the given string and then waits   on the same line  i e   no CRLF   for the user to type a response    lt nul simply pipes an empty response to the set  p command  so the net result is the emitted prompt string   The variable used remains unchanged due to the empty reponse    Problems are  It s not possible to output a leading equal sign  and on Vista leading whitespace characters are removed  but not on XP

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Bail on error   IF   errorlevel   NEQ  0       echo  ERROR   Something broke   Bailing out      exit  B 1

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Recursively search for a string in a directory tree   findstr  S  C  string literal        You can also use regular expressions   findstr  S  R   ERROR    log   Recursive file search   dir  S myfile txt

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The path  with drive  where the script is    dp0  set BAT HOME   dp0 echo  BAT HOME  cd  BAT HOME

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Sneaky trick to wait N seconds  not part of cmd exe but isn t extra software since it comes with Windows   see the ping line   You need N 1 pings since the first ping goes out without a delay       echo  time      call  waitfor 5     echo  time      goto  eof  waitfor     setlocal     set  a  t    1   1       gt nul ping 127 0 0 1 -n  t      endlocal     goto  eof

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if block structure   if   VS90COMNTOOLS           echo  Visual Studio 2008 is not installed   exit  b

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The equivalent of the bash  and other shells   echo -n Hello   or echo Hello  c   which outputs  Hello  without a trailing newline  A cmd hack to do this    lt nul set  p any-variable-name Hello   set  p is a way to prompt the user for input  It emits the given string and then waits   on the same line  i e   no CRLF   for the user to type a response    lt nul simply pipes an empty response to the set  p command  so the net result is the emitted prompt string   The variable used remains unchanged due to the empty reponse    Problems are  It s not possible to output a leading equal sign  and on Vista leading whitespace characters are removed  but not on XP

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Arrays in batch-files   Set a value   set count 1 set var count  42   Extract a value at the command-line   call echo  var count     Extract a value in a batch-file   call echo   var count      Note the extra strafing   signs   The technique may look a little hairy  but it s quite useful  The above will print the contents of var1  i e  42  as we explained  We could also replace the echo command with a set if we wanted to set some other variable to the value in var1  Meaning the following is a valid assignment at the command line   call set x  var count     Then to see the value of va1   echo  x

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if block structure   if   VS90COMNTOOLS           echo  Visual Studio 2008 is not installed   exit  b

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Here how to build a CLASSPATH by scanning a given directory   setlocal ENABLEDELAYEDEXPANSION if defined CLASSPATH  set CLASSPATH  CLASSPATH     else  set CLASSPATH    FOR  R   lib   G IN    jar  DO set CLASSPATH  CLASSPATH    G Echo The Classpath definition is  CLASSPATH    works in XP  or better   With W2K  you need to use a couple of BAT files to achieve the same result  see Include all jars in the classpath definition     It s not needed for 1 6 since you can specify a wildcard directly in CLASSPATH  ex  -cp    lib

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c param for the cmd exe itself  tells it to run and then do these commands   I used to find myself frequently doing   win r  cmd RETURN  ping google com RETURN  but now I just do   win r  cmd  c ping google com RETURN  much faster  also helpful if you re using pstools and you want to use psexec to do some command line function on the remote machine   EDIT   k Works the same  but leaves the prompt open  This might come in handy more often

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You can use errorlevel to check if a given program is available on the system  current dir or path  where your batchfile will run   For this to work the program you are testing for must run  exit and set an exit code when it does   In the example I use -  as an arg to myExe  most CLI programs have a similar arg such as -h  --help  -v etc     this ensures it simply runs and exits leaving or setting errorlevel 0  myExe -   gt nul 2 gt  amp 1  Set errCode  errorlevel   if  errCode  EQU 0       echo myExe -  does not return an error  exists    ELSE       echo myExe -  returns an error  does not exist      Yes  you could test errorlevel directly rather than assigning it to errCode but this way you can have commands between the test and the condition and you test the condition repeatedly as needed

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For parsing stdin from inside a script you need that trick with the FOR and FIND commands   for  f  tokens      g in   find  V      do           do what you want with   g      echo   g

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I have always found it difficult to read comments that are marked by a keyword on each line   REM blah blah blah   Easier to read      blah blah blah

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I have always found it difficult to read comments that are marked by a keyword on each line   REM blah blah blah   Easier to read      blah blah blah

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Quick edit mode in cmd exe is my favorite   This is slightly off topic  but when interacting with the command shell it can be a lifesaver   No  I m not being hyperbolic--you will only see caret-capitol-v a certain number of times before you die  the more you see  the faster you die    Open up regedit  caution  not my fault  blue screen  etc  Go to HKCU Console Set QuickEdit to 1    You can set this from the UI as well  which is probably the better way   See the comments for instructions   Also there s a nice one line script to do this as well    Now  to copy  just left-click and drag to select and right click to copy   To paste  just right click     NO MORE  V V V V V V V V V V V V V V      Crap  I think I just killed somebody   Sorry

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TheSoftwareJedi already mentioned the for command  but I m going to mention it again as it is very powerful   The following outputs the current date in the format YYYYMMDD  I use this when generating directories for backups   for  f  tokens 2-4 delims  -    a in   DATE T   do echo  c b a

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To hide all output from a command redirect to  nul 2  amp 1   For example  the some command line programs display output even if you redirect to  nul  But  if you redirect the output like the line below  all the output will be suppressed   PSKILL NOTEPAD  gt nul 2 gt  amp 1   EDIT  See Ignoring the output of a command for an explanation of how this works

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I have always found it difficult to read comments that are marked by a keyword on each line   REM blah blah blah   Easier to read      blah blah blah

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You can use errorlevel to check if a given program is available on the system  current dir or path  where your batchfile will run   For this to work the program you are testing for must run  exit and set an exit code when it does   In the example I use -  as an arg to myExe  most CLI programs have a similar arg such as -h  --help  -v etc     this ensures it simply runs and exits leaving or setting errorlevel 0  myExe -   gt nul 2 gt  amp 1  Set errCode  errorlevel   if  errCode  EQU 0       echo myExe -  does not return an error  exists    ELSE       echo myExe -  returns an error  does not exist      Yes  you could test errorlevel directly rather than assigning it to errCode but this way you can have commands between the test and the condition and you test the condition repeatedly as needed

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SHIFT   It s a way to iterate through a variable number of arguments passed into a script  or sub-routine  on the command line   In its simplest usage  it shifts  2 to be  1   3 to be  2  and so-on    You can also pass in a parameter to SHIFT to skip multiple arguments    This makes the command  destructive   i e   1 goes away forever   but it allows you to avoid hard-coding a maximum number of supported arguments   Here s a short example to process command-line arguments one at a time    ParseArgs  if   1            goto  DoneParsingArgs    rem     do something with  1      shift  goto  ParseArgs    DoneParsingArgs  rem

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Don t have an editor handy and need to create a batch file   copy con test bat   Just type away the commands  press enter for a new line  Press Ctrl-Z and Enter to close the file

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A method to set the errorlevel to any number you desire   CMD  C EXIT number

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Delayed expansion of variables  with substrings thrown in for good measure         echo off     setlocal enableextensions enabledelayedexpansion     set full  u01 users pax  loop1     if not   full  -1                    set full2  full  -1  full2          set full  full   -1          goto  loop1           echo  full      endlocal

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When passing an unknown number of parameters to a batch file  e g  when several files are dragged and dropped onto the batch file to launch it  you could refer to each parameter variable by name  e g   TYPE  1 TYPE  2 TYPE  3 TYPE  4 TYPE  5    etc   but this gets very messy when you want to check if each parameter exists   if   1  NEQ      TYPE  1   if   2  NEQ      TYPE  2   if   3  NEQ      TYPE  3   if   4  NEQ      TYPE  4   if   5  NEQ      TYPE  5      etc   Also  you can only accept a limited number of parameters with this approach   Instead  try using the SHIFT command    loop IF   1  NEQ      TYPE  1   ELSE   GOTO end   SHIFT GOTO loop  end   SHIFT will move all the parameters down by one  so  2 becomes  1 and  3 becomes  2 etc

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Call Set - Expands Environment variables several levels deep   Found this at http   ss64 com nt call html advanced from answer to another SO question Batch file variables initialized in a for loop  set VarName Param set Param This  call set Answer    Varname    Echo  Answer    gives   set VarName Param set Param This call set Answer  Param  Echo This This

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Being able to run commands and process the output  like backticks of       in bash    for  f  i in   dir  on  b   jpg   do echo --  gt   i   If there are spaces in filenames  use this   for  f  tokens     i in   dir  on  b   jpg   do echo --  gt   i

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I use them as quick shortcuts to commonly used directories   An example file named  sandbox bat  which lives in a directory in my PATH   EXPLORER  C  Documents and Settings myusername Desktop sandbox    Invoking the script is just WIN R --  sandbox

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Command separators   cls  amp  dir copy a b  amp  amp  echo Success copy a b    echo Failure   At the 2nd line  the command after  amp  amp  only runs if the first command is successful   At the 3rd line  the command after    only runs if the first command failed

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Hide input for an interactive batch script      echo off    echo hP1X500P PZBBBfh b  fXf-V   fPf f3 f1 5  u5 gt in com    set  p secret password  Enter password   lt nul    for  f  tokens      i in   in com   do  set secret password   i     del in com

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When using command extensions shell options in a script  it is HIGHLY suggested that you do the following trick at the beginning of your scripts   -- Information pasted from http   www ss64 com nt setlocal html     SETLOCAL will set an ERRORLEVEL if given an argument  It will be zero if one of the two valid arguments is given and one otherwise       You can use this in a batch file to determine if command extensions are available  using the following technique    VERIFY errors 2 gt nul SETLOCAL ENABLEEXTENSIONS IF ERRORLEVEL 1 echo Unable to enable extensions      This works because  VERIFY errors  sets ERRORLEVEL to 1 and then the SETLOCAL will fail to reset the ERRORLEVEL value if extensions are not available  e g  if the script is running under command com       If Command Extensions are permanently disabled then SETLOCAL ENABLEEXTENSIONS will not restore them

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Allows you to change directory based on environment variable without having to specify the     directive  If the variable specified does not exist then try the directory name    if defined  1  call cd     1     else  call cd  1

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Escaping the  plumbing    echo      lt    gt    amp

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Not sure how useful this would be in a batch file  but it s a very convenient command to use in the command prompt   C  some directory gt  start     This will open up Windows Explorer in the  some directory  folder   I have found this a great time-saver

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Integer arithmetic    gt  SET  A result 10 3   1 4

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Being able to run commands and process the output  like backticks of       in bash    for  f  i in   dir  on  b   jpg   do echo --  gt   i   If there are spaces in filenames  use this   for  f  tokens     i in   dir  on  b   jpg   do echo --  gt   i

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To hide all output from a command redirect to  nul 2  amp 1   For example  the some command line programs display output even if you redirect to  nul  But  if you redirect the output like the line below  all the output will be suppressed   PSKILL NOTEPAD  gt nul 2 gt  amp 1   EDIT  See Ignoring the output of a command for an explanation of how this works

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I find the ease with which you can redirect the output of commands to files extremely useful   DIR   txt  gt  tmp txt DIR   exe  gt  gt  tmp txt   Single arrow creates  or overwrites the file  double arrow appends to it   Now I can open tmp txt in my text editor and do all kinds of good stuff

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By using CALL  EXIT  B  SETLOCAL  amp  ENDLOCAL you can implement subroutines with local variables   example    echo off  set x xxxxx call  sub 10 echo  x  exit  b   sub setlocal set  a x  1   1 echo  x  endlocal exit  b   This will print  11 xxxxx   even though  sub modifies x

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The path  with drive  where the script is    dp0  set BAT HOME   dp0 echo  BAT HOME  cd  BAT HOME

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Output a blank line   echo

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PUSHD path   Takes you to the directory specified by path   POPD   Takes you back to the directory you  pushed  from

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Line continuation   call C  WINDOWS system32 ntbackup exe       backup        V yes        R no        RS no        HC off        M normal        L s        daily bks        F daily bkf

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PUSHD path   Takes you to the directory specified by path   POPD   Takes you back to the directory you  pushed  from

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Rather than litter a script with REM or    lines  I do the following at the top of each script    echo OFF goto  START  Description of the script   Usage     myscript -parm1 parm2  gt  result txt   START   Note how you can use the pipe and redirection characters without escaping them

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A handy trick when you want to copy files between branches    C  src branch1 mydir mydir2 mydir3 mydir4 gt xcopy  cd branch1 branch2  foo  Overwrite C  src branch1 mydir mydir2 mydir3 mydir4 foo txt  Yes No All   y C  src branch2 mydir mydir2 mydir3 mydir4 foo txt   This uses both the  cd  environment variable  and environment variable substitution

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You can use call to evaluate names later  leading to some useful properties   call set SomeEnvVariable  extension     somevalue      Using call to set variables whose names depend on other variables  If used with some variable naming rules  you can emulate data collections like arrays or dictionaries by using careful naming rules   The triple   s around somevalue are so it will evaluate to one variable name surrounded by single   s after the call and before set is invoked   This means two   s in a row escape down to a single   character  and then it will expand it again  so somevalue is effectively a name pointer   call set TempVar   SomeEnvVariable  extension      Using it with a temp variable to retrieve the value  which you can then use in logic  This most useful when used in conjunction with delayed variable expansion   To use this method properly  delayed variable expansion needs to be enabled   Because it is off by default  it is best to enable it within the script by putting this as one of the first instructions   setlocal EnableDelayedExpansion

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Not sure how useful this would be in a batch file  but it s a very convenient command to use in the command prompt   C  some directory gt  start     This will open up Windows Explorer in the  some directory  folder   I have found this a great time-saver

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To hide all output from a command redirect to  nul 2  amp 1   For example  the some command line programs display output even if you redirect to  nul  But  if you redirect the output like the line below  all the output will be suppressed   PSKILL NOTEPAD  gt nul 2 gt  amp 1   EDIT  See Ignoring the output of a command for an explanation of how this works

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The subdirectory option on  remove directory    rd  s  q junk

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You can use call to evaluate names later  leading to some useful properties   call set SomeEnvVariable  extension     somevalue      Using call to set variables whose names depend on other variables  If used with some variable naming rules  you can emulate data collections like arrays or dictionaries by using careful naming rules   The triple   s around somevalue are so it will evaluate to one variable name surrounded by single   s after the call and before set is invoked   This means two   s in a row escape down to a single   character  and then it will expand it again  so somevalue is effectively a name pointer   call set TempVar   SomeEnvVariable  extension      Using it with a temp variable to retrieve the value  which you can then use in logic  This most useful when used in conjunction with delayed variable expansion   To use this method properly  delayed variable expansion needs to be enabled   Because it is off by default  it is best to enable it within the script by putting this as one of the first instructions   setlocal EnableDelayedExpansion

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Command separators   cls  amp  dir copy a b  amp  amp  echo Success copy a b    echo Failure   At the 2nd line  the command after  amp  amp  only runs if the first command is successful   At the 3rd line  the command after    only runs if the first command failed

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Extract random lines of text   echo off     Get time  alas  it s only HH MM xM  for  f   a in   time  t   do set zD1   a       Get last digit of MM  set zD2  zD1  4 1        Seed the randomizer  if needed  if not defined zNUM1 set  a zNUM1  zD2       Get a kinda random number  set  a zNUM1 zNUM1   214013   2531011  set  a zNUM2 zNUM1   gt   gt  16   amp  0x7fff      Pull off the first digit      Last digit would be better  but it s late  and I m tired   set zIDX  zNUM2  0 1       Map it down to 0-3  set  a zIDX zIDX 3      Finally  we can set do some proper initialization  set  a zIIDX 0  set zLO   set zLL         Step through each line in the file  looking for line zIDX  for  f  delims      a in  c  lines txt  do call  zoo   zIDX     a      If line zIDX wasn t found  we ll settle for zee LastLine  if   zLO       set zLO  zLL   goto awdun      See if the current line is line zIDX   zoo      Save string of all parms  set zALL         Strip off the first parm  sure hope lines aren t longer than 254 chars   set zWORDS  zALL  2 255       Make this line zee LastLine  set zLL  zWORDS       If this is the line we re looking for  make it zee LineOut  if   1     zIIDX   set zLO  zWORDS       Keep track of line numbers  set  a zIIDX  zIIDX    1  goto  eof      awdun  echo    zLO         Be socially responsible  set zALL   set zD1   set zD2   set zIDX   set zIIDX   set zLL   set zLO      But don t mess with seed    set zNUM1   set zNUM2   set zWORDS

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Redirecting output to the console  even if the batch s output is already redirected to a file via the  gt  con syntax   Example  foo cmd   echo a echo b  gt  con   Calling   foo cmd  gt  output txt   This will result in  a  going to output txt yet  b  going to the console

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When passing an unknown number of parameters to a batch file  e g  when several files are dragged and dropped onto the batch file to launch it  you could refer to each parameter variable by name  e g   TYPE  1 TYPE  2 TYPE  3 TYPE  4 TYPE  5    etc   but this gets very messy when you want to check if each parameter exists   if   1  NEQ      TYPE  1   if   2  NEQ      TYPE  2   if   3  NEQ      TYPE  3   if   4  NEQ      TYPE  4   if   5  NEQ      TYPE  5      etc   Also  you can only accept a limited number of parameters with this approach   Instead  try using the SHIFT command    loop IF   1  NEQ      TYPE  1   ELSE   GOTO end   SHIFT GOTO loop  end   SHIFT will move all the parameters down by one  so  2 becomes  1 and  3 becomes  2 etc

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SHIFT   It s a way to iterate through a variable number of arguments passed into a script  or sub-routine  on the command line   In its simplest usage  it shifts  2 to be  1   3 to be  2  and so-on    You can also pass in a parameter to SHIFT to skip multiple arguments    This makes the command  destructive   i e   1 goes away forever   but it allows you to avoid hard-coding a maximum number of supported arguments   Here s a short example to process command-line arguments one at a time    ParseArgs  if   1            goto  DoneParsingArgs    rem     do something with  1      shift  goto  ParseArgs    DoneParsingArgs  rem

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here s one trick that I use to run My Nant Build script consecutively without having to click the batch file over and over again    CODELINE NANT EXE -buildfile alltargets build -l build log build product  pause GOTO  CODELINE   What will happen is that after your solution finished building  it will be paused  And then if you press any key it will rerun the build script again  Very handy I must say

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Using pushd to a UNC path will create a temporary drive mapping  starting with Z and working backward to find the next available letter  and put you in that drive and path  When you popd or exit the command prompt  the temporary mapping is gone      C   gt pushd   yourmom jukebox     Z   gt pushd   yourmom business     Y   gt    Also  not so much a batch tip as a command-line environment tip  but when you re working at the commandline with pushd and popd and network shares  it s useful to modify your prompt with the     show pushd stack depth  and  M  show network share path       C  utils gt prompt    m p g     C  utils gt pushd m         yourmom pub M   gt pushd c         c   gt pushd    M      C  utils         c   gt popd        yourmom pub M   gt popd     C  utils gt

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The CHOICE command prompts the user for one of multiple options  via a single keypress    echo off echo Please choose one of the following options echo 1  Apple echo 2  Orange echo 3  Pizza echo a  b  c  Something else choice  c 123abc  m  Answer   set ChoiceLevel  ErrorLevel  echo Choice was   ChoiceLevel     ChoiceLevel  will be the nth option selected  in the above example  b 5    More details at the CHOICE reference page on SS64 com

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Subroutines  outputs 42         echo off     call  answer 42     goto  eof  do something     echo  1     goto  eof   and subroutines returning a value  outputs 0  1  2  and so on         echo off     setlocal enableextensions enabledelayedexpansion     call  seq init seq1  loop1     if not  seq1    10           call  seq next seq1         echo  seq1          goto  loop1           endlocal     goto  eof   seq init     set  a   1   -1      goto  eof  seq next     set  a  seq next tmp1    1      set  a   1    seq next tmp1    1      set seq next tmp1      goto  eof

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Quick edit mode in cmd exe is my favorite   This is slightly off topic  but when interacting with the command shell it can be a lifesaver   No  I m not being hyperbolic--you will only see caret-capitol-v a certain number of times before you die  the more you see  the faster you die    Open up regedit  caution  not my fault  blue screen  etc  Go to HKCU Console Set QuickEdit to 1    You can set this from the UI as well  which is probably the better way   See the comments for instructions   Also there s a nice one line script to do this as well    Now  to copy  just left-click and drag to select and right click to copy   To paste  just right click     NO MORE  V V V V V V V V V V V V V V      Crap  I think I just killed somebody   Sorry

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Search and replace when setting environment variables    gt   set fname  date          removes the     from a date for use in timestamped file names   and substrings too      gt   set dayofweek  fname  0 3

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TheSoftwareJedi already mentioned the for command  but I m going to mention it again as it is very powerful   The following outputs the current date in the format YYYYMMDD  I use this when generating directories for backups   for  f  tokens 2-4 delims  -    a in   DATE T   do echo  c b a

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You can chain if statements to get an effect like a short-circuiting boolean  and    if foo if bar baz

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The FOR command   While I hate writing batch files  I m thankful for it   FOR  F  eol   tokens 2 3  delims      i in  myfile txt  do  echo  i  j  k   would parse each line in myfile txt  ignoring lines that begin with a semicolon  passing the 2nd and 3rd token from each line to the for body  with tokens delimited by commas and or spaces  Notice the for body statements reference  i to get the 2nd token   j to get the 3rd token  and  k to get all remaining tokens after the 3rd   You can also use this to iterate over directories  directory contents  etc

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The subdirectory option on  remove directory    rd  s  q junk

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if block structure   if   VS90COMNTOOLS           echo  Visual Studio 2008 is not installed   exit  b

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Total control over output with spacing and escape characters    echo       lt resourceDir  gt   basedir  resources  lt  resourceDir  gt

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Subroutines  outputs 42         echo off     call  answer 42     goto  eof  do something     echo  1     goto  eof   and subroutines returning a value  outputs 0  1  2  and so on         echo off     setlocal enableextensions enabledelayedexpansion     call  seq init seq1  loop1     if not  seq1    10           call  seq next seq1         echo  seq1          goto  loop1           endlocal     goto  eof   seq init     set  a   1   -1      goto  eof  seq next     set  a  seq next tmp1    1      set  a   1    seq next tmp1    1      set seq next tmp1      goto  eof

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Searching for an executable on the path  or other path-like string if necessary    c   gt  for  i in  cmd exe  do  echo     PATH i C  WINDOWS system32 cmd exe  c   gt  for  i in  python exe  do  echo     PATH i C  Python25 python exe  c   gt

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Get the current day  month and year  locale-independently    for  f  tokens 1-4 delims  -      i in   date  t   do  call  set date   i   j   k   l  goto  end set date   set date if    1  0 1   gtr  9   shift for  f  skip 1 tokens 2-4 delims  -     m in   echo   date   do  set   m  1 amp set   n  2 amp set   o  3  goto  eof   end set date  echo day in  DD  format is  dd   month in  MM  format is  mm   year in  YYYY  format is  yy

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Line-based execution  While not a clear benefit in most cases  it can help when trying to update things while they are running   For example   UpdateSource bat  copy UpdateSource bat Current bat echo  Hi     Current bat  copy UpdateSource bat Current bat   Now  executing Current bat produces this output   HI    Watch out though  the batch execution proceeds by line number   An update like this could end up skipping or moving back a line if the essential lines don t have exactly the same line numbers

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Symbolic links   mklink  d directorylink    realdirectory mklink filelink realfile   The command is native on Windows Server 2008 and newer  including Vista and Windows 7    It is also included in some Windows Resource Kits

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Delayed expansion of variables  with substrings thrown in for good measure         echo off     setlocal enableextensions enabledelayedexpansion     set full  u01 users pax  loop1     if not   full  -1                    set full2  full  -1  full2          set full  full   -1          goto  loop1           echo  full      endlocal

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Being able to run commands and process the output  like backticks of       in bash    for  f  i in   dir  on  b   jpg   do echo --  gt   i   If there are spaces in filenames  use this   for  f  tokens     i in   dir  on  b   jpg   do echo --  gt   i

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The FOR command   While I hate writing batch files  I m thankful for it   FOR  F  eol   tokens 2 3  delims      i in  myfile txt  do  echo  i  j  k   would parse each line in myfile txt  ignoring lines that begin with a semicolon  passing the 2nd and 3rd token from each line to the for body  with tokens delimited by commas and or spaces  Notice the for body statements reference  i to get the 2nd token   j to get the 3rd token  and  k to get all remaining tokens after the 3rd   You can also use this to iterate over directories  directory contents  etc

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Search and replace when setting environment variables    gt   set fname  date          removes the     from a date for use in timestamped file names   and substrings too      gt   set dayofweek  fname  0 3

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For loops with numeric counters  outputs 1 through 10    for  l  i in  1 1 10  do echo  i

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Redirecting output to the console  even if the batch s output is already redirected to a file via the  gt  con syntax   Example  foo cmd   echo a echo b  gt  con   Calling   foo cmd  gt  output txt   This will result in  a  going to output txt yet  b  going to the console

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For what it s worth  this is quite a good online reference for Windows CMD or batch files   I learned a few things I didn t know from it

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HELP   When working with different OS version it s important to know what commands are available natively   Typing HELP at the command prompt shows what commands are available  with a brief description of what they do   cmd exe       This will list all the command line parameters for launching a command prompt as well as registry tweaks that change system wide behavior

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PUSHD path   Takes you to the directory specified by path   POPD   Takes you back to the directory you  pushed  from

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Creating an empty file    gt  copy nul filename ext

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FIND as a replacement for grep  I hacked a little  phonebook  for myself with find  Very usefull    echo off  begin set  p term Enter query   type phonebookfile txt  find  i   term   if  errorlevel     0 GOTO  choose echo No entry found set  p new entry Add new entry   echo  new entry   gt  gt  phonebookfile txt   choose set  p action  q uit   n ew query or  e dit   q   if   action     n  GOTO anfang if   action     e        notepad phonebookfile txt     goto  choose     Very fast and effective

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I would say DEBUG EXE is a VERY useful and VERY underused feature of batch files   The DEBUG command allows you to     Assemble and disassemble 16-bit code Read write memory  Modern protected memory makes this considerably less useful   Read data sectors from the hard drive  raw Hex edit  In short  this tool is EXTREMELY powerful  It might not be used much these days anymore  but the power to call up and control this functionality from a batch script adds a staggering amount of power to batch scripting   NOTE  Microsoft has removed this command from 64 bit editions of Windows Xp and Vista and intends to remove it from Windows 7 altogether  from what I ve heard

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the correct format for loops with numeric variables is  for  l   i in  startNumber  counter  endNumber  do echo   i   more details   http   www ss64 com nt for html

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Remove surrounding quote    for  f  useback tokens      a in    str    do set str    a   I recently have to write a batch file that is called by VS prebuild event and I want to pass in the project directory as parameter  In the batch file I need to concatenate the path with nested subfolder name  but first the surrounding quote need to be removed

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Doesn t provide much functionality  but you can use the title command for a couple of uses  like providing status on a long script in the task bar  or just to enhance user feedback    title Searching for        processing search  title preparing search results    data processing

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The IF command  Without it my batch file was junk    echo off IF exist  windir  system32 iexplore exe goto end  echo Hmm    it seems you do not have Internet Explorer  echo Great  You seem to understand      end echo Hmm    You have Internet Explorer  echo That is bad

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With regard to using    instead of REM for comments  be careful     is a special case of a CALL label that acts like a comment  When used inside brackets  for instance in a FOR or IF loop  the function will prematurely exit  Very frustrating to debug    See http   www ss64 com nt rem html for a full description    adding as a new answer instead of a comment to the first mention of this above because I m not worthy of commeting yet  0

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here s one trick that I use to run My Nant Build script consecutively without having to click the batch file over and over again    CODELINE NANT EXE -buildfile alltargets build -l build log build product  pause GOTO  CODELINE   What will happen is that after your solution finished building  it will be paused  And then if you press any key it will rerun the build script again  Very handy I must say

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You can chain if statements to get an effect like a short-circuiting boolean  and    if foo if bar baz

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By using CALL  EXIT  B  SETLOCAL  amp  ENDLOCAL you can implement subroutines with local variables   example    echo off  set x xxxxx call  sub 10 echo  x  exit  b   sub setlocal set  a x  1   1 echo  x  endlocal exit  b   This will print  11 xxxxx   even though  sub modifies x

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A method to set the errorlevel to any number you desire   CMD  C EXIT number

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When using command extensions shell options in a script  it is HIGHLY suggested that you do the following trick at the beginning of your scripts   -- Information pasted from http   www ss64 com nt setlocal html     SETLOCAL will set an ERRORLEVEL if given an argument  It will be zero if one of the two valid arguments is given and one otherwise       You can use this in a batch file to determine if command extensions are available  using the following technique    VERIFY errors 2 gt nul SETLOCAL ENABLEEXTENSIONS IF ERRORLEVEL 1 echo Unable to enable extensions      This works because  VERIFY errors  sets ERRORLEVEL to 1 and then the SETLOCAL will fail to reset the ERRORLEVEL value if extensions are not available  e g  if the script is running under command com       If Command Extensions are permanently disabled then SETLOCAL ENABLEEXTENSIONS will not restore them

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By using CALL  EXIT  B  SETLOCAL  amp  ENDLOCAL you can implement subroutines with local variables   example    echo off  set x xxxxx call  sub 10 echo  x  exit  b   sub setlocal set  a x  1   1 echo  x  endlocal exit  b   This will print  11 xxxxx   even though  sub modifies x

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Local variables are still parsed for the line that ENDLOCAL uses  This allows for tricks like   ENDLOCAL  amp  SET MYGLOBAL  SOMELOCAL   amp  SET MYOTHERGLOBAL  SOMEOTHERLOCAL    This is is a useful way to transmit results to the calling context  Specifically   SOMELOCAL  goes out of scope as soon as ENDLOCAL completes  but by then  SOMELOCAL  is already expanded  so the MYGLOBAL is assigned in the calling context with the local variable   For the same reason  if you decide to do   ENDLOCAL  amp  SET MYLOCAL  MYLOCAL    You ll discover your new MYLOCAL variable is actually now around as a regular environment variable instead of the localized variable you may have intended it to be

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Don t have an editor handy and need to create a batch file   copy con test bat   Just type away the commands  press enter for a new line  Press Ctrl-Z and Enter to close the file

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SHIFT   It s a way to iterate through a variable number of arguments passed into a script  or sub-routine  on the command line   In its simplest usage  it shifts  2 to be  1   3 to be  2  and so-on    You can also pass in a parameter to SHIFT to skip multiple arguments    This makes the command  destructive   i e   1 goes away forever   but it allows you to avoid hard-coding a maximum number of supported arguments   Here s a short example to process command-line arguments one at a time    ParseArgs  if   1            goto  DoneParsingArgs    rem     do something with  1      shift  goto  ParseArgs    DoneParsingArgs  rem

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The path  with drive  where the script is    dp0  set BAT HOME   dp0 echo  BAT HOME  cd  BAT HOME

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List all drives   fsutil fsinfo drives

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Integer arithmetic    gt  SET  A result 10 3   1 4

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Search and replace when setting environment variables    gt   set fname  date          removes the     from a date for use in timestamped file names   and substrings too      gt   set dayofweek  fname  0 3

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Recursively search for a string in a directory tree   findstr  S  C  string literal        You can also use regular expressions   findstr  S  R   ERROR    log   Recursive file search   dir  S myfile txt

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Get the current day  month and year  locale-independently    for  f  tokens 1-4 delims  -      i in   date  t   do  call  set date   i   j   k   l  goto  end set date   set date if    1  0 1   gtr  9   shift for  f  skip 1 tokens 2-4 delims  -     m in   echo   date   do  set   m  1 amp set   n  2 amp set   o  3  goto  eof   end set date  echo day in  DD  format is  dd   month in  MM  format is  mm   year in  YYYY  format is  yy

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With regard to using    instead of REM for comments  be careful     is a special case of a CALL label that acts like a comment  When used inside brackets  for instance in a FOR or IF loop  the function will prematurely exit  Very frustrating to debug    See http   www ss64 com nt rem html for a full description    adding as a new answer instead of a comment to the first mention of this above because I m not worthy of commeting yet  0

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Escaping the  plumbing    echo      lt    gt    amp

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The FOR command   While I hate writing batch files  I m thankful for it   FOR  F  eol   tokens 2 3  delims      i in  myfile txt  do  echo  i  j  k   would parse each line in myfile txt  ignoring lines that begin with a semicolon  passing the 2nd and 3rd token from each line to the for body  with tokens delimited by commas and or spaces  Notice the for body statements reference  i to get the 2nd token   j to get the 3rd token  and  k to get all remaining tokens after the 3rd   You can also use this to iterate over directories  directory contents  etc

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To quickly convert an Unicode text file  16bit char  to a ASCII DOS file  8bit char    C   gt  type unicodeencoded txt  gt  dosencoded txt   as a bonus  if possible  characters are correctly mapped

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forfiles is very useful  for instance  to recursive delete all files older than two days  forfiles  D -2  P  C  Temp   S  C  cmd  c del  path

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Variable substrings    gt  set str 0123456789  gt  echo  str  0 5  01234  gt  echo  str  -5 5  56789  gt  echo  str  3 -3  3456

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Allows you to change directory based on environment variable without having to specify the     directive  If the variable specified does not exist then try the directory name    if defined  1  call cd     1     else  call cd  1

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example of string subtraction on date and time to get file named  YYYY-MM-DD HH MM SS txt      echo test  gt    date  0 4 - date  5 2 - date  8 2   time  0 2   time  3 2   time  6 2  txt    I use color to indicate if my script end up successfully  failed  or need some input by changing color of text and background  It really helps when you have some machine in reach of your view but quite far away     color XY   where X and Y is hex value from 0 to F  where X - background  Y - text  when X   Y color will not change      color Z   changes text color to  Z  and sets black background   color 0  won t work   for names of colors call      color

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Find strings in files in a folder using the pipe     command   dir  b       findstr  f    thepattern

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Total control over output with spacing and escape characters    echo       lt resourceDir  gt   basedir  resources  lt  resourceDir  gt

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When using command extensions shell options in a script  it is HIGHLY suggested that you do the following trick at the beginning of your scripts   -- Information pasted from http   www ss64 com nt setlocal html     SETLOCAL will set an ERRORLEVEL if given an argument  It will be zero if one of the two valid arguments is given and one otherwise       You can use this in a batch file to determine if command extensions are available  using the following technique    VERIFY errors 2 gt nul SETLOCAL ENABLEEXTENSIONS IF ERRORLEVEL 1 echo Unable to enable extensions      This works because  VERIFY errors  sets ERRORLEVEL to 1 and then the SETLOCAL will fail to reset the ERRORLEVEL value if extensions are not available  e g  if the script is running under command com       If Command Extensions are permanently disabled then SETLOCAL ENABLEEXTENSIONS will not restore them

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c param for the cmd exe itself  tells it to run and then do these commands   I used to find myself frequently doing   win r  cmd RETURN  ping google com RETURN  but now I just do   win r  cmd  c ping google com RETURN  much faster  also helpful if you re using pstools and you want to use psexec to do some command line function on the remote machine   EDIT   k Works the same  but leaves the prompt open  This might come in handy more often

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I find the ease with which you can redirect the output of commands to files extremely useful   DIR   txt  gt  tmp txt DIR   exe  gt  gt  tmp txt   Single arrow creates  or overwrites the file  double arrow appends to it   Now I can open tmp txt in my text editor and do all kinds of good stuff

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You can modify a batch file while it is running  For example you can add a forgotten pause to the end of the file while it s running if you wanted to see the results before the batch file quit   see Changing a batch file when its running  I personally think of this more as a gotcha than a feature

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You can use call to evaluate names later  leading to some useful properties   call set SomeEnvVariable  extension     somevalue      Using call to set variables whose names depend on other variables  If used with some variable naming rules  you can emulate data collections like arrays or dictionaries by using careful naming rules   The triple   s around somevalue are so it will evaluate to one variable name surrounded by single   s after the call and before set is invoked   This means two   s in a row escape down to a single   character  and then it will expand it again  so somevalue is effectively a name pointer   call set TempVar   SomeEnvVariable  extension      Using it with a temp variable to retrieve the value  which you can then use in logic  This most useful when used in conjunction with delayed variable expansion   To use this method properly  delayed variable expansion needs to be enabled   Because it is off by default  it is best to enable it within the script by putting this as one of the first instructions   setlocal EnableDelayedExpansion

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A lot of people use GOTO  EOF these days to terminate their batch files  but you can also use EXIT  B for this purpose   The advantage behind using EXIT  B is that you can add an errorlevel after EXIT  B  and it will exit with that errorlevel

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You can use call to evaluate names later  leading to some useful properties   call set SomeEnvVariable  extension     somevalue      Using call to set variables whose names depend on other variables  If used with some variable naming rules  you can emulate data collections like arrays or dictionaries by using careful naming rules   The triple   s around somevalue are so it will evaluate to one variable name surrounded by single   s after the call and before set is invoked   This means two   s in a row escape down to a single   character  and then it will expand it again  so somevalue is effectively a name pointer   call set TempVar   SomeEnvVariable  extension      Using it with a temp variable to retrieve the value  which you can then use in logic  This most useful when used in conjunction with delayed variable expansion   To use this method properly  delayed variable expansion needs to be enabled   Because it is off by default  it is best to enable it within the script by putting this as one of the first instructions   setlocal EnableDelayedExpansion

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The path  with drive  where the script is    dp0  set BAT HOME   dp0 echo  BAT HOME  cd  BAT HOME

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You can chain if statements to get an effect like a short-circuiting boolean  and    if foo if bar baz

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Here how to build a CLASSPATH by scanning a given directory   setlocal ENABLEDELAYEDEXPANSION if defined CLASSPATH  set CLASSPATH  CLASSPATH     else  set CLASSPATH    FOR  R   lib   G IN    jar  DO set CLASSPATH  CLASSPATH    G Echo The Classpath definition is  CLASSPATH    works in XP  or better   With W2K  you need to use a couple of BAT files to achieve the same result  see Include all jars in the classpath definition     It s not needed for 1 6 since you can specify a wildcard directly in CLASSPATH  ex  -cp    lib

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the correct format for loops with numeric variables is  for  l   i in  startNumber  counter  endNumber  do echo   i   more details   http   www ss64 com nt for html

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I find the ease with which you can redirect the output of commands to files extremely useful   DIR   txt  gt  tmp txt DIR   exe  gt  gt  tmp txt   Single arrow creates  or overwrites the file  double arrow appends to it   Now I can open tmp txt in my text editor and do all kinds of good stuff

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This batch file works both with simple files as well as directories as command line parameters  you can mix them in any order   The loop runs the command   echo  in this example  on any specified file  if a parameter is a directory it runs the command recursively on each file in it    echo off for  f  delims     f in   dir     a-d  b  s   do echo   f

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A very old  ca 1990  trick to get the total size of the environment variables   set  gt  test dir test del test

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Output a blank line   echo

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Searching for an executable on the path  or other path-like string if necessary    c   gt  for  i in  cmd exe  do  echo     PATH i C  WINDOWS system32 cmd exe  c   gt  for  i in  python exe  do  echo     PATH i C  Python25 python exe  c   gt

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One of the most common requirements of batch scripting is to log the output generated for later review  Yes  you can redirect the stdout and stderr to a file but then you can t see what is going on unless you tail the log file   So consider running  your batch scripts using a stdout stderr logging utility like logger which will log the output with a timestamp and you are still able to see the script progress as it happens   Yet another stdout stderr logging utility  Yet another stdout stderr logging utility  2010-08-05  Copyright  C  2010 LoRd MuldeR  lt MuldeR2 GMX de gt  Released under the terms of the GNU General Public License  see License txt   Usage    logger exe  logger options    program exe  program arguments    program exe  program arguments    logger exe  logger options    -  Options    -log  lt file name gt   Name of the log file to create  default    lt program gt   lt time gt  log     -append           Append to the log file instead of replacing the existing file   -mode  lt mode gt       Write  stdout  or  stderr  or  both  to log file  default   both     -format  lt format gt   Format of log file   raw  or  time  or  full   default   time     -filter  lt filter gt   Don t write lines to log file that contain this string   -invert           Invert filter  i e  write only lines to log file that match filter   -ignorecase       Apply filter in a case-insensitive way  default  case-sensitive    -nojobctrl        Don t add child process to job object  applies to Win2k and later    -noescape         Don t escape double quotes when forwarding command-line arguments   -silent           Don t print additional information to the console   -priority  lt flag gt   Change process priority  idle belownormal normal abovenormal high    -inputcp  lt cpid gt    Use the specified codepage for input processing  default   utf8     -outputcp  lt cpid gt   Use the specified codepage for log file output  default   utf8

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Create and start editing a new file  copy con new txt This is the contents of my file  Z   Ctrl Z sends the ASCII EOF character  This is like heredocs in bash   cat  lt  lt EOF  gt  new txt This is the contents of my file EOF

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Being able to run commands and process the output  like backticks of       in bash    for  f  i in   dir  on  b   jpg   do echo --  gt   i   If there are spaces in filenames  use this   for  f  tokens     i in   dir  on  b   jpg   do echo --  gt   i

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Much like above  using CALL  EXIT  B  SETLOCAL  amp  ENDLOCAL you can implement functions with local variables and return values   example    echo off  set x xxxxx call  fun 10 echo   x   echo   y   exit  b   fun setlocal set  a y  1   1 endlocal  amp  set x  y  exit  b   This will print    11       The y variable never leaves the local scope  but because of the way CMD resolves a single line at a time  you can extract the value into the x variable in the parent scope

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There is also the EDLIN command  While it may be an old bastard tool once used for line-based text editing  the fact that it s controllable from the command line makes it rather useful for batch scripting  mostly because  just like any other case you d be using EDLIN  it s the only tool available  After all  EDLIN is not a tool you would ordinarily want to use for text editing  unless you are somewhat masochistic  To quote Tim Patterson  the fellow who wrote it    I was aghast when I heard that IBM was using it and not throwing it out the window    NOTE  EDLIN adds old-fashioned EOF  1A  markers to files it edits  If you need to remove them  you ll probably have to use DEBUG

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I have always found it difficult to read comments that are marked by a keyword on each line   REM blah blah blah   Easier to read      blah blah blah

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The CHOICE command prompts the user for one of multiple options  via a single keypress    echo off echo Please choose one of the following options echo 1  Apple echo 2  Orange echo 3  Pizza echo a  b  c  Something else choice  c 123abc  m  Answer   set ChoiceLevel  ErrorLevel  echo Choice was   ChoiceLevel     ChoiceLevel  will be the nth option selected  in the above example  b 5    More details at the CHOICE reference page on SS64 com

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Line continuation   call C  WINDOWS system32 ntbackup exe       backup        V yes        R no        RS no        HC off        M normal        L s        daily bks        F daily bkf

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You can modify a batch file while it is running  For example you can add a forgotten pause to the end of the file while it s running if you wanted to see the results before the batch file quit   see Changing a batch file when its running  I personally think of this more as a gotcha than a feature

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Searching for an executable on the path  or other path-like string if necessary    c   gt  for  i in  cmd exe  do  echo     PATH i C  WINDOWS system32 cmd exe  c   gt  for  i in  python exe  do  echo     PATH i C  Python25 python exe  c   gt

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HELP   When working with different OS version it s important to know what commands are available natively   Typing HELP at the command prompt shows what commands are available  with a brief description of what they do   cmd exe       This will list all the command line parameters for launching a command prompt as well as registry tweaks that change system wide behavior

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The CHOICE command prompts the user for one of multiple options  via a single keypress    echo off echo Please choose one of the following options echo 1  Apple echo 2  Orange echo 3  Pizza echo a  b  c  Something else choice  c 123abc  m  Answer   set ChoiceLevel  ErrorLevel  echo Choice was   ChoiceLevel     ChoiceLevel  will be the nth option selected  in the above example  b 5    More details at the CHOICE reference page on SS64 com

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For loops with numeric counters  outputs 1 through 10    for  l  i in  1 1 10  do echo  i

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Total control over output with spacing and escape characters    echo       lt resourceDir  gt   basedir  resources  lt  resourceDir  gt

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Here how to build a CLASSPATH by scanning a given directory   setlocal ENABLEDELAYEDEXPANSION if defined CLASSPATH  set CLASSPATH  CLASSPATH     else  set CLASSPATH    FOR  R   lib   G IN    jar  DO set CLASSPATH  CLASSPATH    G Echo The Classpath definition is  CLASSPATH    works in XP  or better   With W2K  you need to use a couple of BAT files to achieve the same result  see Include all jars in the classpath definition     It s not needed for 1 6 since you can specify a wildcard directly in CLASSPATH  ex  -cp    lib

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Total control over output with spacing and escape characters    echo       lt resourceDir  gt   basedir  resources  lt  resourceDir  gt

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Line-based execution  While not a clear benefit in most cases  it can help when trying to update things while they are running   For example   UpdateSource bat  copy UpdateSource bat Current bat echo  Hi     Current bat  copy UpdateSource bat Current bat   Now  executing Current bat produces this output   HI    Watch out though  the batch execution proceeds by line number   An update like this could end up skipping or moving back a line if the essential lines don t have exactly the same line numbers

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To set an enivroment variable from the first line of a file  I use this   rem a txt contains one line  abc123 set  p DATA  lt a txt echo data   DATA    This will output  abc123

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Sneaky trick to wait N seconds  not part of cmd exe but isn t extra software since it comes with Windows   see the ping line   You need N 1 pings since the first ping goes out without a delay       echo  time      call  waitfor 5     echo  time      goto  eof  waitfor     setlocal     set  a  t    1   1       gt nul ping 127 0 0 1 -n  t      endlocal     goto  eof

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You can chain if statements to get an effect like a short-circuiting boolean  and    if foo if bar baz

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Much like above  using CALL  EXIT  B  SETLOCAL  amp  ENDLOCAL you can implement functions with local variables and return values   example    echo off  set x xxxxx call  fun 10 echo   x   echo   y   exit  b   fun setlocal set  a y  1   1 endlocal  amp  set x  y  exit  b   This will print    11       The y variable never leaves the local scope  but because of the way CMD resolves a single line at a time  you can extract the value into the x variable in the parent scope

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To get the current date   time to use for log files  etc   I use this in my batch files   for  f  usebackq tokens 1 2 3 4 5 6 7 delims         a in   echo  DATE   TIME    do set NOW   d  b  c   e  f  g set LOG output  NOW  log

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Allows you to change directory based on environment variable without having to specify the     directive  If the variable specified does not exist then try the directory name    if defined  1  call cd     1     else  call cd  1

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here s one trick that I use to run My Nant Build script consecutively without having to click the batch file over and over again    CODELINE NANT EXE -buildfile alltargets build -l build log build product  pause GOTO  CODELINE   What will happen is that after your solution finished building  it will be paused  And then if you press any key it will rerun the build script again  Very handy I must say

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Multiple commands in one line  useful in many situations    amp    Used to combine two commands  executes command1 and then command2  amp  amp   A conditional combination  executes command2 if command1 completes successfully       Command2 executes only if command1 does not complete successfully   Examples         Edit the most recent  TXT file and exit  useful in a  CMD    BAT    FOR  F   I IN   DIR   TXT  B  O -N   DO NOTEPAD   I  amp  EXIT         If exist any  TXT file  display the list in NOTEPAD  if not it        exits without any error  note the  amp  amp  and the 2 gt  error redirection  DIR   TXT  gt  TXT LST 2 gt  NUL  amp  amp  NOTEPAD TXT LST

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Search and replace when setting environment variables    gt   set fname  date          removes the     from a date for use in timestamped file names   and substrings too      gt   set dayofweek  fname  0 3

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c param for the cmd exe itself  tells it to run and then do these commands   I used to find myself frequently doing   win r  cmd RETURN  ping google com RETURN  but now I just do   win r  cmd  c ping google com RETURN  much faster  also helpful if you re using pstools and you want to use psexec to do some command line function on the remote machine   EDIT   k Works the same  but leaves the prompt open  This might come in handy more often

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For parsing stdin from inside a script you need that trick with the FOR and FIND commands   for  f  tokens      g in   find  V      do           do what you want with   g      echo   g

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To quickly convert an Unicode text file  16bit char  to a ASCII DOS file  8bit char    C   gt  type unicodeencoded txt  gt  dosencoded txt   as a bonus  if possible  characters are correctly mapped

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Doskey Macros   I ve long lost the reference for this  but I still think it s a good idea  and worth sharing   We can merge batch-files and doskey scripts into a single file   This might seem a little overly clever  but it works         echo off    rem Call DOSKEY and use this file as the macrofile     SystemRoot  system32 doskey  listsize 1000  macrofile  0     rem In batch mode  jump to the end of the file    goto end     Doskey aliases h doskey  history     File listing enhancements ls dir  x        Directory navigation up cd    pd pushd      end    rem                                                                       rem   EOF - Don t remove the following line   It clears out the         rem   macro  Were using it because there is no support for comments    rem   in a DOSKEY macro file     rem                                                                         It works by defining a fake doskey macro     which is gracefully  or silently  ignored when it is interpreted as a batch-file   I ve shortened the version listed here  if you want more  go here

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Quick edit mode in cmd exe is my favorite   This is slightly off topic  but when interacting with the command shell it can be a lifesaver   No  I m not being hyperbolic--you will only see caret-capitol-v a certain number of times before you die  the more you see  the faster you die    Open up regedit  caution  not my fault  blue screen  etc  Go to HKCU Console Set QuickEdit to 1    You can set this from the UI as well  which is probably the better way   See the comments for instructions   Also there s a nice one line script to do this as well    Now  to copy  just left-click and drag to select and right click to copy   To paste  just right click     NO MORE  V V V V V V V V V V V V V V      Crap  I think I just killed somebody   Sorry

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Doskey Macros   I ve long lost the reference for this  but I still think it s a good idea  and worth sharing   We can merge batch-files and doskey scripts into a single file   This might seem a little overly clever  but it works         echo off    rem Call DOSKEY and use this file as the macrofile     SystemRoot  system32 doskey  listsize 1000  macrofile  0     rem In batch mode  jump to the end of the file    goto end     Doskey aliases h doskey  history     File listing enhancements ls dir  x        Directory navigation up cd    pd pushd      end    rem                                                                       rem   EOF - Don t remove the following line   It clears out the         rem   macro  Were using it because there is no support for comments    rem   in a DOSKEY macro file     rem                                                                         It works by defining a fake doskey macro     which is gracefully  or silently  ignored when it is interpreted as a batch-file   I ve shortened the version listed here  if you want more  go here

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PAUSE   Stops execution and displays the following prompt   Press any key to continue        Useful if you want to run a batch by double-clicking it in Windows Explorer and want to actually see the output rather than just a flash of the command window

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c param for the cmd exe itself  tells it to run and then do these commands   I used to find myself frequently doing   win r  cmd RETURN  ping google com RETURN  but now I just do   win r  cmd  c ping google com RETURN  much faster  also helpful if you re using pstools and you want to use psexec to do some command line function on the remote machine   EDIT   k Works the same  but leaves the prompt open  This might come in handy more often

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Delayed expansion of variables  with substrings thrown in for good measure         echo off     setlocal enableextensions enabledelayedexpansion     set full  u01 users pax  loop1     if not   full  -1                    set full2  full  -1  full2          set full  full   -1          goto  loop1           echo  full      endlocal

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The CHOICE command prompts the user for one of multiple options  via a single keypress    echo off echo Please choose one of the following options echo 1  Apple echo 2  Orange echo 3  Pizza echo a  b  c  Something else choice  c 123abc  m  Answer   set ChoiceLevel  ErrorLevel  echo Choice was   ChoiceLevel     ChoiceLevel  will be the nth option selected  in the above example  b 5    More details at the CHOICE reference page on SS64 com

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List all drives   fsutil fsinfo drives

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example of string subtraction on date and time to get file named  YYYY-MM-DD HH MM SS txt      echo test  gt    date  0 4 - date  5 2 - date  8 2   time  0 2   time  3 2   time  6 2  txt    I use color to indicate if my script end up successfully  failed  or need some input by changing color of text and background  It really helps when you have some machine in reach of your view but quite far away     color XY   where X and Y is hex value from 0 to F  where X - background  Y - text  when X   Y color will not change      color Z   changes text color to  Z  and sets black background   color 0  won t work   for names of colors call      color

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forfiles is very useful  for instance  to recursive delete all files older than two days  forfiles  D -2  P  C  Temp   S  C  cmd  c del  path

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Multiple commands in one line  useful in many situations    amp    Used to combine two commands  executes command1 and then command2  amp  amp   A conditional combination  executes command2 if command1 completes successfully       Command2 executes only if command1 does not complete successfully   Examples         Edit the most recent  TXT file and exit  useful in a  CMD    BAT    FOR  F   I IN   DIR   TXT  B  O -N   DO NOTEPAD   I  amp  EXIT         If exist any  TXT file  display the list in NOTEPAD  if not it        exits without any error  note the  amp  amp  and the 2 gt  error redirection  DIR   TXT  gt  TXT LST 2 gt  NUL  amp  amp  NOTEPAD TXT LST

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FIND as a replacement for grep  I hacked a little  phonebook  for myself with find  Very usefull    echo off  begin set  p term Enter query   type phonebookfile txt  find  i   term   if  errorlevel     0 GOTO  choose echo No entry found set  p new entry Add new entry   echo  new entry   gt  gt  phonebookfile txt   choose set  p action  q uit   n ew query or  e dit   q   if   action     n  GOTO anfang if   action     e        notepad phonebookfile txt     goto  choose     Very fast and effective

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I would say DEBUG EXE is a VERY useful and VERY underused feature of batch files   The DEBUG command allows you to     Assemble and disassemble 16-bit code Read write memory  Modern protected memory makes this considerably less useful   Read data sectors from the hard drive  raw Hex edit  In short  this tool is EXTREMELY powerful  It might not be used much these days anymore  but the power to call up and control this functionality from a batch script adds a staggering amount of power to batch scripting   NOTE  Microsoft has removed this command from 64 bit editions of Windows Xp and Vista and intends to remove it from Windows 7 altogether  from what I ve heard

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Redirecting output to the console  even if the batch s output is already redirected to a file via the  gt  con syntax   Example  foo cmd   echo a echo b  gt  con   Calling   foo cmd  gt  output txt   This will result in  a  going to output txt yet  b  going to the console

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Symbolic links   mklink  d directorylink    realdirectory mklink filelink realfile   The command is native on Windows Server 2008 and newer  including Vista and Windows 7    It is also included in some Windows Resource Kits

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Inline comments using  amp         This is my batch file which does stuff  copy thisstuff thatstuff   amp    We need to make a backup in case we screw up          do lots of other stuff   How does this work   It s an ugly hack   The  amp  is the command separator roughly approximating the   of UNIX shells   The    is another ugly hack that kinda-sorta emulates a REM statement   The end result is that you execute your command and then you execute a do-nothing command  thus approximating a comment   This doesn t work in all situations  but it works often enough to be a useful hack

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Not sure how useful this would be in a batch file  but it s a very convenient command to use in the command prompt   C  some directory gt  start     This will open up Windows Explorer in the  some directory  folder   I have found this a great time-saver

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example of string subtraction on date and time to get file named  YYYY-MM-DD HH MM SS txt      echo test  gt    date  0 4 - date  5 2 - date  8 2   time  0 2   time  3 2   time  6 2  txt    I use color to indicate if my script end up successfully  failed  or need some input by changing color of text and background  It really helps when you have some machine in reach of your view but quite far away     color XY   where X and Y is hex value from 0 to F  where X - background  Y - text  when X   Y color will not change      color Z   changes text color to  Z  and sets black background   color 0  won t work   for names of colors call      color

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Rather than litter a script with REM or    lines  I do the following at the top of each script    echo OFF goto  START  Description of the script   Usage     myscript -parm1 parm2  gt  result txt   START   Note how you can use the pipe and redirection characters without escaping them

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Multiple commands in one line  useful in many situations    amp    Used to combine two commands  executes command1 and then command2  amp  amp   A conditional combination  executes command2 if command1 completes successfully       Command2 executes only if command1 does not complete successfully   Examples         Edit the most recent  TXT file and exit  useful in a  CMD    BAT    FOR  F   I IN   DIR   TXT  B  O -N   DO NOTEPAD   I  amp  EXIT         If exist any  TXT file  display the list in NOTEPAD  if not it        exits without any error  note the  amp  amp  and the 2 gt  error redirection  DIR   TXT  gt  TXT LST 2 gt  NUL  amp  amp  NOTEPAD TXT LST

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Inline comments using  amp         This is my batch file which does stuff  copy thisstuff thatstuff   amp    We need to make a backup in case we screw up          do lots of other stuff   How does this work   It s an ugly hack   The  amp  is the command separator roughly approximating the   of UNIX shells   The    is another ugly hack that kinda-sorta emulates a REM statement   The end result is that you execute your command and then you execute a do-nothing command  thus approximating a comment   This doesn t work in all situations  but it works often enough to be a useful hack

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Remove surrounding quote    for  f  useback tokens      a in    str    do set str    a   I recently have to write a batch file that is called by VS prebuild event and I want to pass in the project directory as parameter  In the batch file I need to concatenate the path with nested subfolder name  but first the surrounding quote need to be removed

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The equivalent of the bash  and other shells   echo -n Hello   or echo Hello  c   which outputs  Hello  without a trailing newline  A cmd hack to do this    lt nul set  p any-variable-name Hello   set  p is a way to prompt the user for input  It emits the given string and then waits   on the same line  i e   no CRLF   for the user to type a response    lt nul simply pipes an empty response to the set  p command  so the net result is the emitted prompt string   The variable used remains unchanged due to the empty reponse    Problems are  It s not possible to output a leading equal sign  and on Vista leading whitespace characters are removed  but not on XP

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With regard to using    instead of REM for comments  be careful     is a special case of a CALL label that acts like a comment  When used inside brackets  for instance in a FOR or IF loop  the function will prematurely exit  Very frustrating to debug    See http   www ss64 com nt rem html for a full description    adding as a new answer instead of a comment to the first mention of this above because I m not worthy of commeting yet  0

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The goto  eof pasteboard  I add  goto  eof  to end of my scripts as a handy space for code fragments  That way I can quickly copy paste to and from this area  without having to comment uncomment   goto  eof    code scraps call this bat call that bat set TS  DATE  10  DATE  4 2  DATE  7 2 - TIME  0 2  TIME  3 2  TIME  6   for  R C  temp    G in    bak  DO del   G

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TheSoftwareJedi already mentioned the for command  but I m going to mention it again as it is very powerful   The following outputs the current date in the format YYYYMMDD  I use this when generating directories for backups   for  f  tokens 2-4 delims  -    a in   DATE T   do echo  c b a

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Rather than litter a script with REM or    lines  I do the following at the top of each script    echo OFF goto  START  Description of the script   Usage     myscript -parm1 parm2  gt  result txt   START   Note how you can use the pipe and redirection characters without escaping them

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Setting environment variables from a file with SET  P  SET  P SVNVERSION  lt ver tmp

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Escaping the  plumbing    echo      lt    gt    amp

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PAUSE   Stops execution and displays the following prompt   Press any key to continue        Useful if you want to run a batch by double-clicking it in Windows Explorer and want to actually see the output rather than just a flash of the command window

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This batch file works both with simple files as well as directories as command line parameters  you can mix them in any order   The loop runs the command   echo  in this example  on any specified file  if a parameter is a directory it runs the command recursively on each file in it    echo off for  f  delims     f in   dir     a-d  b  s   do echo   f

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I really like this Windows XP Commands reference  as well as the Syntax link at the top  it covers many of the tips and tricks already found in other answers

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Sneaky trick to wait N seconds  not part of cmd exe but isn t extra software since it comes with Windows   see the ping line   You need N 1 pings since the first ping goes out without a delay       echo  time      call  waitfor 5     echo  time      goto  eof  waitfor     setlocal     set  a  t    1   1       gt nul ping 127 0 0 1 -n  t      endlocal     goto  eof

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Creating an empty file    gt  copy nul filename ext

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Line continuation   call C  WINDOWS system32 ntbackup exe       backup        V yes        R no        RS no        HC off        M normal        L s        daily bks        F daily bkf

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The IF command  Without it my batch file was junk    echo off IF exist  windir  system32 iexplore exe goto end  echo Hmm    it seems you do not have Internet Explorer  echo Great  You seem to understand      end echo Hmm    You have Internet Explorer  echo That is bad

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Output a blank line   echo

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Doesn t provide much functionality  but you can use the title command for a couple of uses  like providing status on a long script in the task bar  or just to enhance user feedback    title Searching for        processing search  title preparing search results    data processing

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Extract random lines of text   echo off     Get time  alas  it s only HH MM xM  for  f   a in   time  t   do set zD1   a       Get last digit of MM  set zD2  zD1  4 1        Seed the randomizer  if needed  if not defined zNUM1 set  a zNUM1  zD2       Get a kinda random number  set  a zNUM1 zNUM1   214013   2531011  set  a zNUM2 zNUM1   gt   gt  16   amp  0x7fff      Pull off the first digit      Last digit would be better  but it s late  and I m tired   set zIDX  zNUM2  0 1       Map it down to 0-3  set  a zIDX zIDX 3      Finally  we can set do some proper initialization  set  a zIIDX 0  set zLO   set zLL         Step through each line in the file  looking for line zIDX  for  f  delims      a in  c  lines txt  do call  zoo   zIDX     a      If line zIDX wasn t found  we ll settle for zee LastLine  if   zLO       set zLO  zLL   goto awdun      See if the current line is line zIDX   zoo      Save string of all parms  set zALL         Strip off the first parm  sure hope lines aren t longer than 254 chars   set zWORDS  zALL  2 255       Make this line zee LastLine  set zLL  zWORDS       If this is the line we re looking for  make it zee LineOut  if   1     zIIDX   set zLO  zWORDS       Keep track of line numbers  set  a zIIDX  zIIDX    1  goto  eof      awdun  echo    zLO         Be socially responsible  set zALL   set zD1   set zD2   set zIDX   set zIIDX   set zLL   set zLO      But don t mess with seed    set zNUM1   set zNUM2   set zWORDS

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Append files using copy   copy file1 txt file2 txt file3 txt append txt   Also  to set all CLI parameters to a single variable   SET MSG      This will take every word  or symbol  that is separated by spaces and save it to a single batch file variable  Technically  each parameter is  1   2   3  etc   but this SET command uses a wildcard to reference every parameter in stdin   Batch File    SET MSG     echo  MSG    Command Line   C  test gt test bat Hello World  Hello World

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I use them as quick shortcuts to commonly used directories   An example file named  sandbox bat  which lives in a directory in my PATH   EXPLORER  C  Documents and Settings myusername Desktop sandbox    Invoking the script is just WIN R --  sandbox

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here s one trick that I use to run My Nant Build script consecutively without having to click the batch file over and over again    CODELINE NANT EXE -buildfile alltargets build -l build log build product  pause GOTO  CODELINE   What will happen is that after your solution finished building  it will be paused  And then if you press any key it will rerun the build script again  Very handy I must say

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PUSHD path   Takes you to the directory specified by path   POPD   Takes you back to the directory you  pushed  from

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Find strings in files in a folder using the pipe     command   dir  b       findstr  f    thepattern

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Findstr with regular expression support   findstr    0-9     c  windows system32 drivers etc hosts

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A handy trick when you want to copy files between branches    C  src branch1 mydir mydir2 mydir3 mydir4 gt xcopy  cd branch1 branch2  foo  Overwrite C  src branch1 mydir mydir2 mydir3 mydir4 foo txt  Yes No All   y C  src branch2 mydir mydir2 mydir3 mydir4 foo txt   This uses both the  cd  environment variable  and environment variable substitution

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By using CALL  EXIT  B  SETLOCAL  amp  ENDLOCAL you can implement subroutines with local variables   example    echo off  set x xxxxx call  sub 10 echo  x  exit  b   sub setlocal set  a x  1   1 echo  x  endlocal exit  b   This will print  11 xxxxx   even though  sub modifies x

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Variable substrings    gt  set str 0123456789  gt  echo  str  0 5  01234  gt  echo  str  -5 5  56789  gt  echo  str  3 -3  3456

[windows] Hidden features of Windows batch files

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