What does 755 mean?

The numeric representation 755 in file permissions indicates the following:

• The first digit (7) represents the owner's permissions.
• The second digit (5) represents the group's permissions.
• The third digit (5) represents others' permissions.

Breakdown of 755:

• Owner (7): The owner has read (4), write (2), and execute (1) permissions. The sum is 4 + 2 + 1 = 7.
• Group (5): The group has read (4) and execute (1) permissions, but no write permission. The sum is 4 + 1 = 5.
• Others (5): Others also have read (4) and execute (1) permissions, but no write permission. The sum is 4 + 1 = 5.

Summary

So, 755 means:

• The owner can read, write, and execute the file.
• The group can read and execute the file, but cannot modify it.
• Others can also read and execute the file, but cannot modify it.