Question about terminal in mac os x system

Question

linux

Hello everyone, I ask for the help of Unix and MacOS experts.
While studying the basic Unix commands, I came across an incomprehensible thing to me when outputting the ls command - l
To the right of the file permissions, an incomprehensible @ sign appears opposite some files.

Example:
MacBook-Air-Dmitrij:Desktop tooq$ ls -l
[email protected] 1 tooq staff 854390 Sep 25 21:23 picture.jpg
[email protected] 1 tooq staff 18138785 24 Sep 17:09 Symphony_1.mp3
-rw-r--r-- 2 tooq staff 6 25 Sep 23:03 file.txt
-rw-r--r-- 2 tooq staff 6 25 Sep 23:03

tex The university does not know what it means, but as he understood, this is not part of the Unix terminal, but some kind of feature of MacOS. Maybe someone knows what kind of dog this is, I tried to google, but I did not find anything ...

Answer 1

The answer was found here .
"... If a file or folder has extended attributes this is displayed with a '@' symbol immediately after the access rights, if a file or folder has additional security settings (access list cintrol ACL) this is displayed with a plus sign '+' immediately after the access rights. "

Answer 2

usually this means under MacOS that there is an additional attribute (text encoding, photo viewing, translation)
look like this:ls [email protected]

Answer 3

Indicates the presence of extended attributes.
man xattr

Answer 4

www.flester.com/blog/2008/01/03/mac-os-x-leopard-ls1-output

Answer 5

habrahabr.ru/qa/45282/ - here the same question was asked
by gerry.ws/2010/04/1314/managing-files-with-extended-attributes-on-mac-os-x.html - it is described in detail and how review and remove