/boot
Boot files are stored here, including the configuration of the boot loader, the ker‐
nel, and any initial ramdisk files needed to boot the kernel.
/dev
A pseudofilesystem that contains entries for hardware devices for programs to
access.
/etc
Configuration files related to the operating system and system services.
/home
The directory containing the user’s home directories.
/lib
Library files that contain shared code and functions that any program can use.
/opt
Optional, third-party software is loaded here.
/proc
A pseudofilesystem that has directories containing files related to running pro‐
cesses, including memory maps, the command line used to run the program, and
other essential system information related to the program.
/root
The home directory of the root user.
/sbin
System binaries that also need to be available in single-user mode.
/tmp
Temporary files are stored here.
/usr
Read-only user data (includes bin, doc, lib, sbin, and share subdirectories).
/var
Variable data including state information about running processes, log files, run‐
time data, and other temporary files. All of these files are expected to change in
size or existence during the running of the system.
You can also see the owner (user) and group, both of which are root in these cases.
This is followed by the file size, the last time the file or directory was modified, and
then the name of the file or directory. You may notice at the top that there are files
that start with a dot, or period. The dot files and directories store user-specific set‐
tings and logs. Because they are managed by the applications that create them, as a
general rule, they are hidden from regular directory listings.
