Things listed under the directory: ls
d is the file type, "r-xr-xr-x" are the file owner, file owning group, and access to everyone else (rwx, read-write executables), 2 is the number of hard links to the file, root-bit file owner, behind the root file belongs to the user group, the number is 49152 bytes, followed by the date and time the file was last modified, and finally the file name.
Everything is a file.
"-" at the beginning of the file are common: 
"D" is the beginning of the file directory: 
File "b" is the beginning of the block device file
File "c" is the beginning of the character device file
File "s" at the beginning of the file are socket
File "p" is the beginning of the pipeline file
"L" is the beginning of the soft links: 
linux directory:
