From the command line in Linux, “stat” is a useful command.  Good luck committing it’s 30+ options to memory….  Here’s the help output for easy reference to study if you’re so inclined. I probably use %U and %G the most when I run into file permission issues and realized I cleared the Symfony cache accidentally under the “root” user because I was in the CLI running Composer updates or installing other server-level scripts.

[~/public_html/app]# stat --help

Usage: stat [OPTION]… FILE…

Display file or file system status.

-L, –dereference follow links
-Z, –context print the SELinux security context
-f, –file-system display file system status instead of file status
-c –format=FORMAT use the specified FORMAT instead of the default;
output a newline after each use of FORMAT
–printf=FORMAT like –format, but interpret backslash escapes,
and do not output a mandatory trailing newline.
If you want a newline, include \n in FORMAT.
-t, –terse print the information in terse form

–help display this help and exit

–version output version information and exit

The valid format sequences for files (without –file-system):

%a Access rights in octal
%A Access rights in human readable form
%b Number of blocks allocated (see %B)
%B The size in bytes of each block reported by %b
%C SELinux security context string
%d Device number in decimal
%D Device number in hex
%f Raw mode in hex
%F File type
%g Group ID of owner
%G Group name of owner
%h Number of hard links
%i Inode number
%n File name
%N Quoted file name with dereference if symbolic link
%o I/O block size
%s Total size, in bytes
%t Major device type in hex
%T Minor device type in hex
%u User ID of owner
%U User name of owner
%x Time of last access
%X Time of last access as seconds since Epoch
%y Time of last modification
%Y Time of last modification as seconds since Epoch
%z Time of last change
%Z Time of last change as seconds since Epoch

Valid format sequences for file systems:

%a Free blocks available to non-superuser
%b Total data blocks in file system
%c Total file nodes in file system
%d Free file nodes in file system
%f Free blocks in file system
%C SELinux security context string
%i File System ID in hex
%l Maximum length of filenames
%n File name
%s Block size (for faster transfers)
%S Fundamental block size (for block counts)
%t Type in hex
%T Type in human readable form

In Linux, “cd” your way to the directory you want to completely clean out, then type:

$  rm –rf *

I suggest going into the directory first, then “ls” to list the contents so you can see what you’re deleting before using this command, though! Just a reminder, the prompt symbol is the “$” you don’t type that, on PCs or Macs it’s sometimes a % symbol instead.