In Linux, you can give permissions to files and folders using two methods:
1. Numeric Method and
2. Symbolic Method.
1. Numeric Method:
In the numeric method, numbers 0 to 7 set the permissions. This method is called the Octal Method because it assigns permissions using octal (base-8) numbers. Each digit in the sequence represents a specific category:
- Rightmost digit → Others
- Middle digit → Group
- Leftmost digit → User (owner)
Each number is a combination of read (r), write (w), and execute (x) permissions.
Example:
chmod 754 file.txt
7 → User: read + write + execute
5 → Group: read + execute
4 → Others: read onlyThe numeric method gives permissions to files and folders in Linux in this way.
2. Symbolic Method:
In the symbolic method, permissions are assigned using letters and operators instead of numbers.
Letters:
- r → read
- w → write
- x → execute
Operators:
- + → add a permission
- - → remove a permission
- = → set a specific permission
Categories:
- u → user (owner)
- g → group
- o → others
- a → all (user + group + others)
Example:
chmod u=rwx,g=rx,o=r file.txt
u=rwx → User (owner) has read, write, and execute permissions
g=rx → Group has read and execute permissions
o=r → Others have read-only permission