bash script:var doc

Linux/Bash Script/5-Variables.md

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+# 🧮 Bash Variables
+
+In **Bash scripting**, **variables** are used to store values like text or numbers. They allow scripts to be dynamic and reusable.
+
+---
+
+## ✍️ Defining Variables
+
+Variables are created **without spaces** around the `=` sign:
+
+```bash
+user="ali"
+age=21
+```
+
+* `user` is assigned the value `"ali"`.
+* `age` is assigned the value `21`.
+
+> ✅ Tip: No `let` or `var` is needed like in other programming languages.
+
+---
+
+## 📢 Using Variables
+
+You can **access variables** by prefixing them with `$`:
+
+```bash
+user="radin"
+echo "Welcome, $user"
+```
+
+**Output:**
+
+```
+Welcome, radin
+```
+
+---
+
+## 🧪 Full Script Example
+
+Here's a complete Bash script using variables:
+
+```bash
+#!/bin/bash
+
+user="mmd"
+age=25
+
+echo "$user is $age years old."
+```
+
+**Output:**
+
+```
+mmd is 25 years old.
+```
+
+---
+
+## 📌 Notes
+
+* Variable names are **case-sensitive** (`User` and `user` are different).
+* Avoid spaces around `=` when assigning.
+* Enclose variable values in quotes if they contain spaces.
+
+---
+
+## ✅ Summary
+
+| Task            | Syntax                       |
+| --------------- | ---------------------------- |
+| Define variable | `name="value"`               |
+| Use variable    | `$name`                      |
+| Print value     | `echo "$name"`               |
+| With script     | Use `#!/bin/bash` at the top |
+