FreeDOS help system (hhstndrd 1.0.8 en)[if]

Command: if

IF performs conditional processing in batch programs. IF is a BATCH-FILE / AUTOEXEC.BAT command. It can also be used in command line.


IF [NOT] ERRORLEVEL number command IF [NOT] string1==string2 command IF [NOT] EXIST filename command drive The drive letter, e.g. C: path The directory, e.g. \example\ filename The file, e.g. test.txt


NOT Specifies that the command shell should carry out the command only if the condition is false. (Without this, the command will be run if the condition is true.) ERRORLEVEL number Specifies a true condition if the last program run returned an exit code equal to or greater than the number specified. command Specifies the command to carry out if the condition is met. string1==string2 Specifies a true condition if the specified text strings match. EXIST filename Specifies a true condition if the specified filename exists.


ERRORLEVEL number: DOS Programs return a number when they exit, which sometimes contains information on whether the program was successful. If the last program to exit returned the given number, then the condition is true. string1==string2 If the two strings of characters are equal, then the condition is true. exist [drive][path] If the given file is there, then the condition filename is true. IF is a command internal to and needs no other file in order to work.


IN A .BAT FILE / AUTOEXEC.BAT: if exist c:\kernel.sys ECHO Kernel exists (gives a message if kernel exists) set A=freedos set B=freedos set C=otherdos if %A%==%B% ECHO A and B are same string (A and B are "freedos", so the message will appear) if %A%==%C% ECHO A and C are same string (A is "freedos", C is "otherdos", so no message will appear) if not %A%==%C% ECHO A and C are not same string (A is "freedos", C is "otherdos", as they are NOT the same, the message will appear)

See also:

autoexec.bat batch files choice goto ------------------------------------------------------------------------------ Copyright (C) 2003 Robert Platt, updated 2007 and 2020 by W. Spiegl. This file is derived from the FreeDOS Spec Command HOWTO. See the file H2Cpying for copying conditions.