Linux文件权限

References

What are special file permissions?

Special permissions are available for files and directories and provide additional privileges over the standard permission sets that have been covered.

SUID is the special permission for the user access level and always executes as the user who owns the file, no matter who is passing the command.
SGID allows a file to be executed as the group owner of the file; a file created in the directory has its group ownership set to the directory owner. This is helpful for directories used collaboratively among different members of a group because all members can access and execute new files.

The "sticky bit" is a directory-level special permission that restricts file deletion, meaning only the file owner can remove a file within the directory.