Linux Directory Structure

 Useful Information of Linux Directory Structure.

root directory:

/bin – binary or executable programs.

/etc – system configuration files.

/home – home directory. It is the default current directory.

/opt – optional or third-party software.

/tmp – temporary space.

/usr – User related programs.

/var – log files.

System Configuration Files:

/etc/bashrc – It is used by bash shell that contains system defaults and aliases.

/etc/crontab – A shell script to run specified commands on a predefined time interval.

/etc/exports – It contains information on the file system available on the network.

/etc/fstab – Information of the Disk Drive and their mount point.

/etc/group – It is a text file to define Information of Security Group.

/etc/grub.conf – It is the grub bootloader configuration file.

/etc/init.d – Service startup Script.

/etc/lilo.conf – It contains lilo bootloader configuration file.

/etc/hosts – Information of IP and corresponding hostnames.

/etc/hosts.allow – It contains a list of hosts allowed accessing services on the local machine.

/etc/host.deny – List of hosts denied to access services on the local machine.

/etc/inittab – INIT process and their interaction at the various run level.

/etc/issue – Allows editing the pre-login message.

/etc/modules.conf – It contains the configuration files for the system modules.

/etc/motd – It contains the message of the day.

/etc/mtab – Currently mounted blocks information.

/etc/passwd – It contains username, password of the system, users in a shadow file.

/etc/printcap – It contains printer Information.

/etc/profile – Bash shell defaults.

/etc/profile.d –  It contains other scripts like application scripts, executed after login.

/etc/rc.d – It avoids script duplication.

/etc/rc.d/init.d – Run Level Initialisation Script.

/etc/resolv.conf – DNS being used by System.

/etc/security – It contains the name of terminals where root login is possible.

/etc/skel – Script that initiates new user home directory.

/etc/termcap – An ASCII file that defines the behavior of different types of the terminal.

/etc/X11 –  Directory tree contains all the conf files for the X-window System.

User Related Files:

/usr/bin – It contains most of the executable files.

/usr/bin/X11 – Symbolic link of /usr/bin.

/usr/include – It contains standard include files used by C program.

/usr/share – It contains architecture independent shareable text files.

/usr/lib – It contains object files and libraries.

/usr/sbin – It contains commands for Super User, for System Administration.

Virtual and Pseudo Process Related Files:

/proc/cpuinfo – CPU Information

/proc/filesystems – It keeps the useful info about the processes that are running currently.

/proc/interrupts – it keeps the information about the number of interrupts per IRQ.

/proc/ioports – Contains all the Input and Output addresses used by devices on the server.

/proc/meminfo –  It reports the memory usage information.

/proc/modules – Currently using kernel module.

/proc/mount – Mounted File-system Information.

/proc/stat –  It displays the detailed statistics of the current system.

/proc/swaps –  It contains swap file information.

Version Information File:

/version – It displays the Linux version information.

Log Files:

/var/log/lastlog – It stores user last login info.

/var/log/messages – It has all the global system messages.

/var/log/wtmp – It keeps a history of login and logout information.