/* steve jansen */

// another day in paradise hacking code and more

Windows Batch Scripting: If/Then Conditionals

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Computers are all about 1’s and 0’s, right? So, we need a way to handle when some condition is 1, or else do something different when it’s 0.

The good news is DOS has pretty decent support for if/then/else conditions.

Checking that a File or Folder Exists

IF EXIST "temp.txt" ECHO found

Or the converse:

IF NOT EXIST "temp.txt" ECHO not found

Both the true condition and the false condition:

IF EXIST "temp.txt" (
    ECHO found
) ELSE (
    ECHO not found

NOTE: It’s a good idea to always quote both operands (sides) of any IF check. This avoids nasty bugs when a variable doesn’t exist, which causes the the operand to effectively disappear and cause a syntax error.

Checking If A Variable Is Not Set

IF "%var%"=="" (SET var=default value)


IF NOT DEFINED var (SET var=default value)

Checking If a Variable Matches a Text String

SET var=Hello, World!

IF "%var%"=="Hello, World!" (
    ECHO found

Or with a case insensitive comparison

IF /I "%var%"=="hello, world!" (
    ECHO found

Artimetic Comparisons

SET /A var=1

IF /I "%var%" EQU "1" ECHO equality with 1

IF /I "%var%" NEQ "0" ECHO inequality with 0

IF /I "%var%" GEQ "1" ECHO greater than or equal to 1

IF /I "%var%" LEQ "1" ECHO less than or equal to 1

Checking a Return Code

    ECHO execution failed

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