How do I interpret file permissions?

File permissions in Linux are represented by a series of characters that indicate what actions users can perform on a file or directory. Here's how to interpret them:

Format:

Permissions are displayed in a format like this:

-rw-r--r--

Breakdown:

File Type:
- The first character indicates the type:
  - -: Regular file
  - d: Directory
  - l: Symbolic link
Permissions:
The next nine characters are divided into three groups of three:
- Owner Permissions (first three characters):
  - r: Read permission
  - w: Write permission
  - x: Execute permission
- Group Permissions (next three characters):
  - Same meanings as above, but for the group that owns the file.
- Other Permissions (last three characters):
  - Same meanings as above, but for all other users.

Example:

For the permissions -rw-r--r--:

-: It's a regular file.
rw-: The owner can read and write, but not execute.
r--: The group can read, but not write or execute.
r--: Others can read, but not write or execute.

Numeric Representation:

Permissions can also be represented numerically:

Read (r) = 4
Write (w) = 2
Execute (x) = 1

You can add these values to represent permissions:

rwx = 7 (4+2+1)
rw- = 6 (4+2+0)
r-- = 4 (4+0+0)

Example Numeric:

For -rw-r--r--, the numeric representation is 644:

Owner: rw- = 6
Group: r-- = 4
Others: r-- = 4

If you have more questions or need further clarification, feel free to ask!