Hidden features of Windows batch files

Output a blank line:

echo.

The subdirectory option on 'remove directory':

rd /s /q junk

For loops with numeric counters (outputs 1 through 10):

for /l %i in (1,1,10) do echo %i

To quickly convert an Unicode text file (16bit/char) to a ASCII DOS file (8bit/char).

C:\> type unicodeencoded.txt > dosencoded.txt

as a bonus, if possible, characters are correctly mapped.

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> start .

This will open up Windows Explorer in the "some_directory" folder.

I have found this a great time-saver.

if block structure:

if "%VS90COMNTOOLS%"=="" (
echo: Visual Studio 2008 is not installed
exit /b
)

By using CALL, EXIT /B, SETLOCAL & 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.

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.

You can chain if statements to get an effect like a short-circuiting boolean `and'.

if foo if bar baz

Multiple commands in one line, useful in many situations:

& Used to combine two commands, executes command1 and then command2
&& 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 & EXIT


:: ** If exist any .TXT file, display the list in NOTEPAD, if not it
:: ** exits without any error (note the && and the 2> error redirection)
DIR *.TXT > TXT.LST 2> NUL && NOTEPAD TXT.LST