Set a variable: SET FOO="bar"
Use a variable: echo %FOO%
Command line arguments are variables: %1, %2 etc.
Check if a variable is defined: IF NOT DEFINED FOO SET FOO="bar". Useful for testing command line arguments.
Check a result code from the last executed command: IF ERRORLEVEL $n $CMD-TO-EXECUTE. It executes the command if result code is equal or greater to $n, so to check for any failures use 1.
Do things in a loop: FOR /L %%A IN (1,1,10) DO @echo hello
Execute another script: call another.bat
Check if directory exists: IF EXIST e:\directory GOTO USE_E
Here’s an example of a batch file that does a few common things:
@ECHO OFF
@rem "pushd $dir" puts $dir on directory stack
pushd .
SET COMMENT=%1
IF NOT DEFINED COMMENT SET COMMENT=""
SET FOO="bar"
IF %FOO%=="bar" goto IS_BAR
echo The above should always be true
goto END
:IS_BAR
nmake -f Makefile.vc
IF ERRORLEVEL 1 goto ERR_ONE_OR_HIGHER
echo Compilation successful!
goto END
:ERR_ONE_OR_HIGHER
echo Compilation failed!
goto END
:END
@rem popd pops the directory name from the stack and does cd there
popd