File access permissions on UNIX-like systems such as Linux

I researched file access permissions on UNIX-like systems such as Linux and am leaving a note here. Please tell me if anything is incorrect.

ls -lをMacOSでやると、こういうのが出てくる。

❯ ls -al
total 1632
drwxr-xr-x@ 206 my-name  staff   6592 Nov  5 16:17 .
drwx------@ 785 my-name  staff  25120 Nov  5 15:50 ..
-rw-r--r--@   1 my-name  staff  12292 Nov  5 16:18 .DS_Store
drwxr-xr-x@  80 my-name  staff   2560 Nov  5 16:16 001-039
-rw-rw-r--@   1 my-name  staff     32 Nov  5 16:00 001.csv
-rw-rw-r--@   1 my-name  staff     14 May 11  2022 001.txt
...

It’s a command to list files, but what’s that -rw-rw-r--@ on the left?

Permission notation on UNIX-like systems

According to what I found, UNIX-like OSes express permissions in this way. The leading - and the following three groups represent permissions for user, group, and others.

Breaking down -rw-rw-r--@ gives - | rw- | rw- | r-- | @.

• The first character is either - or d; d indicates the entry is a directory.
• The subsequent groups of three characters indicate permissions (described below).
  • The three-character group repeats three times. The first is the owning user, the next is the owning group, and the last is other users.
  • In the example -rw-rw-r--@ 1 my-name staff 14 May 11 2022 001.txt, my-name is the owner, and staff is the owning group.
  • If it’s rwxrwxrwx, everything is permitted.
• The trailing @ indicates extended attributes are present on certain OSes like macOS. (On some OSes it might be +?)
  • The rwxrwxrwx settings alone aren’t always sufficient, so macOS adds extra information.

Explanation of permission types

Their meanings are as follows:

If read and write are allowed but execute is not, it would look like rw-.