Understanding Permission (r,w,x)

Linux permissions control:

1. Who can access files
2. Who can modify files
3. Who can execute programs

Permissions are one of the most important Linux security features.

Permission Types

Symbol	Meaning	Value
r	Read	4
w	Write	2
x	Execute	1

Check Permissions

Use:

ls -l

Example Output

• rwxr-xr-- 1 aryan dev 1200 file.sh

Permission Breakdown

• rwxr-xr--

Split into:

• rwx r-x r--

Meaning

Part	Who
rwx	Owner permissions
r-x	Group permissions
r--	Others permissions

First Character Meaning

Symbol	Type
-	Regular file
d	Directory
l	Link

Read Permission (r)

File

Allows viewing content.

Example:

cat file.txt

Directory

Allows listing files.

Example:

ls folder

Write Permission (w)

File

Allows:

1. Edit
2. Modify
3. Delete contents

Directory

Allows:

1. Create files
2. Delete files
3. Rename files

Execute Permission (x)

File

Allows running file as program/script.

Example:

./script.sh

Directory

Allows entering directory.

Example:

cd folder

Permission Groups

Linux permissions apply to:

Group	Meaning
User (u)	Owner
Group (g)	Group members
Others (o)	Everyone else

Example

• rwxr-x---

Meaning:

User	Permission
Owner	Read, Write, Execute
Group	Read, Execute
Others	No access

Numeric Permission System

Permission	Value
r	4
w	2
x	1

Example

755

Means:

User	Permission
Owner	rwx (7)
Group	r-x (5)
Others	r-x (5)