151 lines
3.2 KiB
Markdown
151 lines
3.2 KiB
Markdown
# 📁 Linux File Permissions: A Quick & Clear Guide
|
|
|
|
---
|
|
|
|
## 🔍 Example: Output of `ls -lh`
|
|
|
|
Run this command in your terminal:
|
|
|
|
```bash
|
|
ls -lh
|
|
```
|
|
|
|
Example output:
|
|
|
|
```bash
|
|
drwxr-xr-x 3 root root 4.0K Jul 1 22:22 dir1
|
|
-rw-r--r-- 1 root root 2.0G Jul 1 21:59 test2.tar
|
|
```
|
|
|
|
---
|
|
|
|
## 🧠 Understanding the Output Columns
|
|
|
|
| Column | Description |
|
|
| -------------------- | --------------------------------------- |
|
|
| `d` / `-` | File type (`d` = directory, `-` = file) |
|
|
| `rwxr-xr-x` | Permissions (user, group, others) |
|
|
| `3` | Number of hard links |
|
|
| `root` | Owner (user) |
|
|
| `root` | Group |
|
|
| `4.0K` / `2.0G` | File size |
|
|
| `Jul 1 22:22` | Last modification date |
|
|
| `dir1` / `test2.tar` | File or directory name |
|
|
|
|
---
|
|
|
|
## 🔤 First Character: File Type Indicator
|
|
|
|
* `d` → Directory 📂
|
|
* `-` → Regular file 📄
|
|
|
|
---
|
|
|
|
## 🔠 File Permissions Breakdown
|
|
|
|
```
|
|
drwxr-xr-x
|
|
│││ │ │ │
|
|
│││ │ │ └─ Permissions for Others (o)
|
|
│││ │ └── Permissions for Group (g)
|
|
│││ └──── Permissions for User (u)
|
|
│└──────── File type (d = directory, - = file)
|
|
└───────── Read (r), Write (w), Execute (x)
|
|
```
|
|
|
|
---
|
|
|
|
## 🔐 Permission Symbols Explained
|
|
|
|
| Symbol | Meaning |
|
|
| ------ | ------- |
|
|
| `r` | Read |
|
|
| `w` | Write |
|
|
| `x` | Execute |
|
|
|
|
---
|
|
|
|
## 👥 Permission Entities
|
|
|
|
| Symbol | Meaning |
|
|
| ------ | ------------ |
|
|
| `u` | User (owner) |
|
|
| `g` | Group |
|
|
| `o` | Others |
|
|
| `a` | All |
|
|
|
|
---
|
|
|
|
## 🔢 Numeric Permission Values (Octal)
|
|
|
|
| Value | Binary | Permissions | Meaning |
|
|
| ----- | ------ | ----------- | ---------------------- |
|
|
| 0 | 000 | --- | No permissions |
|
|
| 1 | 001 | --x | Execute only |
|
|
| 2 | 010 | -w- | Write only |
|
|
| 3 | 011 | -wx | Write + Execute |
|
|
| 4 | 100 | r-- | Read only |
|
|
| 5 | 101 | r-x | Read + Execute |
|
|
| 6 | 110 | rw- | Read + Write |
|
|
| 7 | 111 | rwx | Read + Write + Execute |
|
|
|
|
---
|
|
|
|
## 🛠️ Changing Permissions with `chmod`
|
|
|
|
### Syntax:
|
|
|
|
```bash
|
|
chmod [permissions] [filename]
|
|
```
|
|
|
|
### Example (numeric):
|
|
|
|
```bash
|
|
chmod 755 myscript.sh
|
|
```
|
|
|
|
### What does `755` mean?
|
|
|
|
| Entity | Value | Permission |
|
|
| ------ | ----- | -------------------------- |
|
|
| User | 7 | rwx (read, write, execute) |
|
|
| Group | 5 | r-x (read, execute) |
|
|
| Others | 5 | r-x (read, execute) |
|
|
|
|
### Recursive permission change:
|
|
|
|
```bash
|
|
chmod -R <permission> <directory>
|
|
```
|
|
|
|
---
|
|
|
|
## 👑 Changing Ownership with `chown`
|
|
|
|
### Syntax:
|
|
|
|
```bash
|
|
chown [options] owner[:group] file
|
|
```
|
|
|
|
### Examples:
|
|
|
|
Change owner only:
|
|
|
|
```bash
|
|
sudo chown radin file.txt
|
|
```
|
|
|
|
Change owner and group:
|
|
|
|
```bash
|
|
sudo chown radin:dev file.txt
|
|
```
|
|
|
|
Change owner and group recursively (for directories):
|
|
|
|
```bash
|
|
sudo chown -R radin:dev files/
|
|
```
|