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content/command-line/concepts/bash/terms/conditional-statements/conditional-statements.md

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+---
+Title: 'Conditional Statements'
+Description: 'Allow a script to make decisions based on conditions.'
+Subjects:
+  - 'Bash/Shell'
+  - 'Computer Science'
+Tags:
+  - 'Bash/Shell'
+  - 'Command Line'
+  - 'Script'
+  - 'Conditionals'
+CatalogContent:
+  - 'learn-the-command-line'
+  - 'paths/computer-science'
+---
+
+Conditional statements in Bash allow a script to make decisions based on conditions. These statements help in controlling the flow of execution by performing different actions based on whether a condition evaluates to true or false. Bash supports several types of conditional checks, including comparisons between numbers, strings, and file conditions.
+
+## Syntax
+
+Bash conditional statements are typically written using `if`, `elif`, `else`, and `fi` keywords. The basic syntax is:
+
+```pseudo
+if [ condition ]; then
+  # Code to execute if condition is true
+elif [ another_condition ]; then
+  # Code to execute if another_condition is true
+else
+  # Code to execute if no conditions are met
+fi
+```
+
+### Basic Operators
+
+The different operators that Bash provides can be classified into several categories based on the data type of the operands.
+
+**Numeric Operators:**
+
+| Operator | Description              |
+| -------- | ------------------------ |
+| `-eq`    | Equal to                 |
+| `-ne`    | Not equal to             |
+| `-lt`    | Less than                |
+| `-le`    | Less than or equal to    |
+| `-gt`    | Greater than             |
+| `-ge`    | Greater than or equal to |
+
+**String Operators:**
+
+| Operator | Description         |
+| -------- | ------------------- |
+| `=`      | Equal to            |
+| `!=`     | Not equal to        |
+| `-z`     | String is empty     |
+| `-n`     | String is not empty |
+
+**File Test Operators:**
+
+| Operator | Description            |
+| -------- | ---------------------- |
+| `-e`     | File exists            |
+| `-f`     | File is a regular file |
+| `-d`     | File is a directory    |
+| `-r`     | File is readable       |
+| `-w`     | File is writable       |
+| `-x`     | File is executable     |
+
+## Example
+
+Here is an example that takes a number from the user and then uses conditional statements in Bash to check if the number is greater than, less than, or equal to 0:
+
+```bash
+#!/bin/bash
+
+read -p "Enter a number: " num
+
+if [ "$num" -gt 0 ]; then
+  echo "The number is positive."
+elif [ "$num" -lt 0 ]; then
+  echo "The number is negative."
+else
+  echo "The number is zero."
+fi
+```
+
+The above code produces the following output if the user inserts the number 5 when prompted:
+
+```shell
+Enter a number: 5
+The number is positive.
+```