1. What is Unix Chmod?

The chmod command in Unix and Unix-like operating systems is used to change the access permissions of file system objects. It's an essential command for system administrators and users who need to control who can read, write, or execute their files.

2. How Does the Calculator Work?

The calculator uses the standard Unix permission formula:

Where:

• Read permission = 4
• Write permission = 2
• Execute permission = 1

Explanation: The calculator sums these values for user, group, and others to produce a 3-digit octal number representing the permissions.

3. Understanding Permission Values

Details: The three-digit permission number represents:

• First digit: Owner (user) permissions
• Second digit: Group permissions
• Third digit: Others (world) permissions

Common permission values include 755 (rwxr-xr-x) and 644 (rw-r--r--).

4. Using the Calculator

Tips: Check the boxes for the permissions you want to grant to user, group, and others. The calculator will compute the corresponding chmod value.

5. Frequently Asked Questions (FAQ)

Q1: What does 755 permission mean?
A: 755 means the owner can read, write, and execute (7), while group and others can read and execute (5).

Q2: What's the most restrictive permission?
A: 000 means no one has any permissions. 400 means only the owner can read.

Q3: What's the difference between 644 and 755?
A: 644 doesn't grant execute permission to anyone, while 755 grants execute to owner, group, and others.

Q4: How do I set permissions for directories?
A: Directories need execute permission to be accessible. Typical directory permission is 755.

Q5: What's the symbolic equivalent of 750?
A: rwxr-x--- (owner: rwx, group: r-x, others: no permissions)