Linux /root and its architecture!

Guide outline

1.1. Overview
1.2. The Root Directory
1.3. /bin
1.4. /boot
1.5. /dev
1.6. /etc
1.7. /home
1.8. /initrd
1.9. /lib
1.10. /lost+found
1.11. /media
1.12. /mnt
1.13. /opt
1.14. /proc
1.15. /root
1.16. /sbin
1.17. /usr
1.18. /var
1.19. /srv
1.20. /tm
2. Glossary

Additional Linux Resources

Here is a list of resources for learning Linux:

Resources for System Administrators

Linux System Admin Guide- What is Linux Operating System and how it works
Linux System Admin Guide- What are Directory Tree and Filesystem Hierarchy in Linux
Linux System Admin Guide- Introduction to Linux File Systems for System Admins
Linux System Admin Guide- Overview of Linux Virtual Memory and Disk Buffer Cache
Linux System Admin Guide- Best Practices for Monitoring Linux Systems
Linux System Admin Guide- Best Practices for Performing Linux Boots and Shutdowns
Linux System Admin Guide- Best Practices for Making and Managing Backup Operations

Resources for Linux Kernel Programmers

How Linux Operating System Memory Management works
Comprehensive Review of Linux Kernel Operating System Processes
Comprehensive Review of Linux File System Architecture and Management
What are mechanisms behind Linux Kernel task management
How Linux Kernel Sources and Functions work
Comprehensive look at how Linux Data Structures work

Hands-on Linux classes

Linux Operating System Distributions

Comprehensive list of all Linux OS distributions
Comprehensive list of all special purpose Linux distributions
Comprehensive list of all secure Linux distributions for cybersecurity professionals

1.2. The Root Directory

To comply with the FSSTND the following directories, or symbolic links to directories, are required in /.


       /bin       Essential command binaries
       /boot      Static files of the boot loader
       /dev       Device files
       /etc       Host-specific system configuration
       /lib       Essential shared libraries and kernel modules
       /media     Mount point for removeable media
       /mnt       Mount point for mounting a filesystem temporarily
       /opt       Add-on application software packages
       /sbin      Essential system binaries
       /srv       Data for services provided by this system
       /tmp       Temporary files
       /usr       Secondary hierarchy
       /var       Variable data


The following directories, or symbolic links to directories, must be in /, if the corresponding subsystem is installed:


     / -- the root directory
     /home User home directories (optional)
     /lib<qual> Alternate format essential shared libraries
     /root Home directory for the root user (optional)


Each directory listed above is described in detail in separate subsections further on in this document.

The reference system will be based upon Debian 3.0r0 (Woody), 2.4.18 kernel configured to a Redhat kernel-2.4.18-i686.config file.





  • Intel Celeron 766 Processor
  • MSI MS-6309 V.2.0 Mainboard
  • 512MB PQI PC133 SDRAM
  • 16x Lite-On LTD-165H DVD-ROM
  • 40x24x10 Sony CRX175A1 CD-RW
  • D-Link DFE-530TX 10/100 NIC
  • Realtek RTL8029(AS) 10 NIC
  • Lucent Mars2 Linmodem
  • C-Media CMI8738 PCI Audio Device
  • Miro DC-30 VIVO
  • Aopen KF-45A Miditower Case
  • Acer Accufeel Keyboard
  • Genius Netscroll+ Mouse
  • Compaq MV500 Presario Monitor




  • Windows XP on /dev/hda1
  • FreeBSD 4.2 on /dev/hda2
  • Redhat 8.0 on /dev/hda5
  • Debian 3.0r0 on /dev/hda6
  • Mandrake 9.1 on /dev/hda7
  • Swap partition on /dev/hda8



As we all know Linux file system starts with /, the root directory. All other directories are ‘children’ of this directory. The partition which the root file system resides on is mounted first during boot and the system will not boot if it doesn’t find it. On our reference system, the root directory contains the following sub-directories:

bin/ dev/ home/ lost+found/ proc/ sbin/ usr/ cdrom/ opt/ vmlinuz boot/ etc/ lib/ mnt/ root/ tmp/ var/ dvd/ floppy/ initrd/ /tftpboot

In days past it was also the home directory of ‘root’ but now he has been given his own directory for reasons that will be explained further on in this document.