By | February 15, 2022

Department ID: 6dda6e949d602062


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File syntax
   IF [NOT] EXIST filename command

   IF [NOT] EXISTS filename (command) ELSE (command)

String Syntax
   IF [/I] [NO] item1==item2 command
   IF [/I] [NOT] command "item1" == "item2"

   IF [/I] comparison operation element1 command element2

   IF [/I] item1 comparison operation item2 (command) ELSE (command)

error checking syntax
   IF [NO] DEFINED command variable

   IF [NOT] ERRORLEVEL Number received


   element A string of text or an environment variable, whichever is more complex.
               Comparison by variable can be modified withsubstring or search syntax.

   command The command to execute.

  filename Test file or general model.

  DO NOT run the command if the sickness is false.

   == Execute the command if the two lines match.

  /I Perform a case-independent comparison of companies.

   Compare-op will be one of
                ECV: Same
                NEQ: not the same

                LSS: Minus except <
                LEQ: Less than or equal to <=

                GTR: More because >
                GEQ: Greater than or >=

 equals This 3-character syntax is probably necessary because > then <
                Symbols are more common than redirect operators

IF parses numbers when used inclusively (EQU, NEQ, LSS, LEQ, GTR, GEQ).
The user == comparison always results in a string comparison.


There are two different handlers for checking the error level. The first syntax ( IF ERRORLEVEL ...) provides compatibility with earlier batch videos from doslogic.com 95 days.
The second method is to use the %ERRORLEVEL% variable available in Windows 2.000 or later.ERRORLEVEL

if n statements should be read asto IF errorlevel >= number
if 0 returns TRUE, it doesn't matter if the error level is 0, 9 or 5 or 64 ERRORLEVEL
if 1 returns TRUE whether most error level is 1 or 5 64
IF NOT ERRORLEVEL means 1, and if ERRORLEVEL is less than 7 (zero or negative).
It's not very clear or user friendly and doesn't make it easy to account for error numbers.

Using the %ERRORLEVEL% variable is a useful and more logical way to check error levels:

IF %ERRORLEVEL% NEQ Echo 0 Error detected
IF %ERRORLEVEL% EQU Echo 1 No errors found

IF %ERRORLEVEL% EQU 0 (no error echo detected) ELSE (error echo detected)
IF %ERRORLEVEL% EQU Echo 0 No error found || Echo Error detected

This allows you to detect errors that can be negative numbers, as well as check for specific errors:
IF %ERRORLEVEL% EQU 64 ...deliberately

To invoke a large ERRORLEVEL level in a batch script, use the EXIT /B command.

It is possible (though not too optimistic) to create a string aspect called %ERRORLEVEL% (user variable)
if present, these types are Variables override the %ERRORLEVEL% system variable and prevent it from being read by commands such as ECHO and IF.

Test Whether Variable Is Empty

To find out if a sales string parameter exists, use empty parentheses, for example:

IF [%1]==[] no ECHO value
IF EQU [%1] [] ECHO
value missing

When comparing against an adjustment that can be empty, we need a pair of square brackets [ ] so that if the variable was empty, the IF command would still have something to lease: IF[]EQU[] will return True .

Actually, you can use almost any character, '~' or curly braces, } { even the number 4, but the square brackets are chosen because they have no special meaning.
When dealing with filenames/paths you should always quote them, if %_myvar% contains "C:\Some Path" then the correct comparison would be IF ["C:\Some Path"] EQU []< br>