How to use the command "if" (with examples)

The “if” command in batch scripting is used to perform conditional processing. It allows you to execute specific commands based on whether a condition is true or false. This command is widely used in batch scripts for automating tasks and making decisions based on certain criteria.

Use case 1: Execute the specified commands if the condition is true

Code:

if condition (echo Condition is true)

Motivation: This use case is helpful when you want to perform specific actions only if a certain condition is met. For example, you may want to display a message if a particular file exists.

Explanation: The “if” command followed by a condition enclosed in parentheses is used here. If the condition evaluates to true, the commands written within the parentheses will be executed.

Example Output: If the condition is true, the output will be “Condition is true”.

Use case 2: Execute the specified commands if the condition is false

Code:

if not condition (echo Condition is true)

Motivation: This use case allows you to execute commands when a particular condition is false. It is useful when you need to perform actions only if a specific condition is not met.

Explanation: The “if not” command followed by a condition enclosed in parentheses is used here. If the condition evaluates to false, the commands within the parentheses will be executed.

Example Output: If the condition is false, the output will be “Condition is true”.

Use case 3: Execute the first specified commands if the condition is true otherwise execute the second specified commands

Code:

if condition (echo Condition is true) else (echo Condition is false)

Motivation: This use case is handy when you want to execute different commands based on whether a condition is true or false. It allows you to have alternate actions depending on the result of the condition.

Explanation: The “if” command followed by a condition enclosed in parentheses is used along with the “else” keyword. If the condition is true, the commands specified before the “else” keyword will be executed. Otherwise, the commands after the “else” keyword will be executed.

Example Output: If the condition is true, the output will be “Condition is true”. If the condition is false, the output will be “Condition is false”.

Use case 4: Check whether %errorlevel% is greater than or equal to the specified exit code

Code:

if errorlevel 2 (echo Condition is true)

Motivation: This use case allows you to check the errorlevel value and perform specific actions based on its value. It is commonly used to handle different error codes and execute commands accordingly.

Explanation: The “if errorlevel” command followed by a specific exit code is used here. If the errorlevel value is greater than or equal to the specified code, the commands within the parentheses will be executed.

Example Output: If the errorlevel value is 2 or higher, the output will be “Condition is true”.

Use case 5: Check whether two strings are equal

Code:

if %variable% == string (echo Condition is true)

Motivation: This use case is useful when you need to compare two strings and perform actions based on their equality. It allows you to execute specific commands only if the strings match.

Explanation: The “if” command is used here along with the equality operator “==”. The %variable% represents a variable that holds a string value. If the variable value is equal to the specified string, the commands within the parentheses will be executed.

Example Output: If the variable’s value is equal to the string, the output will be “Condition is true”.

Use case 6: Check whether two strings are equal without respecting letter case

Code:

if /i %variable% == string (echo Condition is true)

Motivation: This use case is similar to the previous one, but it ignores the case sensitivity while comparing the strings. It is valuable when you want to compare strings without considering whether they are uppercase or lowercase.

Explanation: The “/i” flag is used with the “if” command to make the string comparison case-insensitive. The %variable% represents a variable that holds a string value. If the variable value is equal to the specified string (regardless of letter case), the commands within the parentheses will be executed.

Example Output: If the variable’s value is equal to the string (ignoring case), the output will be “Condition is true”.

Use case 7: Check whether a file exists

Code:

if exist path\to\file (echo Condition is true)

Motivation: This use case allows you to check the existence of a file and perform specific actions based on its availability. It is commonly used to handle file-related operations and paths.

Explanation: The “if exist” command followed by the path to a file (including the file name) is used here. If the specified file exists, the commands within the parentheses will be executed.

Example Output: If the file at the specified path exists, the output will be “Condition is true”.

Conclusion

The “if” command is a powerful tool in batch scripting for performing conditional processing. It enables you to make decisions and execute commands based on various conditions such as file existence, string equality, error level, and general boolean expressions. Understanding the different use cases of the “if” command can greatly enhance your ability to automate tasks and create robust batch scripts.