Zsh (Z shell) is a popular shell program for Unix-like operating systems, known for its powerful scripting capabilities. In this blog post, we will explore how to set up conditional statements in Zsh scripts. Conditional statements allow us to make decisions and execute different code blocks based on certain conditions.

if 문

The if statement is used to perform different actions based on the success or failure of a command. It follows the following syntax:

if condition
then
    # statements to be executed if condition is true
else
    # statements to be executed if condition is false
fi

Here, the condition is typically a command or test expression that returns either a true or false value. If the condition is true, the statements within the then block are executed. Otherwise, the statements within the else block are executed.

Let’s consider an example where we want to check if a file exists and display a corresponding message:

if [[ -f myfile.txt ]]
then
    echo "File exists!"
else
    echo "File does not exist!"
fi

In this example, the condition [[ -f myfile.txt ]] checks if the file myfile.txt exists. If it does, the “File exists!” message is displayed; otherwise, the “File does not exist!” message is displayed.

case 문

The case statement allows us to match a variable against multiple patterns and execute code based on the matching pattern. It follows the following syntax:

case variable in
    pattern1)
        # statements to be executed if variable matches pattern1
        ;;
    pattern2)
        # statements to be executed if variable matches pattern2
        ;;
    pattern3)
        # statements to be executed if variable matches pattern3
        ;;
    *)
        # statements to be executed if variable does not match any pattern
        ;;
esac

Let’s consider an example where we want to perform different actions based on the value of a variable called fruit:

case $fruit in
    "apple")
        echo "Selected fruit is an apple."
        ;;
    "banana")
        echo "Selected fruit is a banana."
        ;;
    *)
        echo "Unknown fruit selected."
        ;;
esac

In this example, we match the value of the variable fruit against different patterns. Depending on the value, a corresponding message is displayed.

조건문 비교 연산자

Zsh provides various comparison operators to evaluate conditions. Some commonly used comparison operators include:

• -eq : equal to
• -ne : not equal to
• -gt : greater than
• -lt : less than
• -ge : greater than or equal to
• -le : less than or equal to

Here’s an example that demonstrates the usage of comparison operators:

number=10

if [[ $number -gt 5 ]]
then
    echo "The number is greater than 5."
fi

In this example, we check if the value of the variable number is greater than 5 using the -gt comparison operator. If it is true, the corresponding message is displayed.

With these conditional statements and comparison operators, you can create more complex logic in your Zsh scripts and perform different actions based on conditions. This flexibility allows for efficient and powerful scripting in the Zsh shell.

Start exploring Zsh’s scripting capabilities and enhance your Linux scripting experience with conditional statements. Happy scripting!