hierarchical directory structure

/
The root directory, where everything begins.		 /bin Contains binaries (programs) that must be present for the system to boot and run.
/boot Contains the Linux kernel, initial RAM disk image (for drivers needed at boot time), and the boot loader. Interesting files include /boot/grub/grub.conf, or menu.lst, which is used to configure the boot loader, and /boot/vmlinuz (or something similar), the Linux kernel.
/dev This is a special directory that contains device nodes. “Everything is a file” also applies to devices. Here is where the kernel maintains a list of all the devices it understands.
/etc The /etc directory contains all the system-wide configuration files. It also contains a collection of shell scripts that start each of the system services at boot time. Everything in this directory should be readable text. While everything in /etc is interesting, here are some all-time favorites: /etc/crontab, a file that defines when automated jobs will run; /etc/fstab, a table of storage devices and their associated mount points; and /etc/passwd, a list of the user accounts.
/home In normal configurations, each user is given a directory in /home. Ordinary users can write files only in their home directories. This limitation protects the system from errant user activity.
/lib Contains shared library files used by the core system programs. These are similar to dynamic link libraries (DLLs) in Windows.
/lost+found Each formatted partition or device using a Linux file system, such as
ext3, will have this directory. It is used in the case of a partial recov￾ery from a file system corruption event. Unless something really bad
has happened to your system, this directory will remain empty.
/media On modern Linux systems, the /media directory will contain the mount points for removable media such as USB drives, CD-ROMs, and so on, that are mounted automatically at insertion.
/mnt On older Linux systems, the /mnt directory contains mount points for removable devices that have been mounted manually.
/opt The /opt directory is used to install “optional” software. This is mainly used to hold commercial software products that might be installed on the system.
/proc The /proc directory is special. It’s not a real file system in the sense of files stored on your hard drive. Rather, it is a virtual file system main￾tained by the Linux kernel. The “files” it contains are peepholes into the kernel itself. The files are readable and will give you a picture of how the kernel sees your computer.
/root This is the home directory for the root account.
/sbin This directory contains “system” binaries. These are programs that perform vital system tasks that are generally reserved for the superuser.
/tmp The /tmp directory is intended for the storage of temporary, transient files created by various programs. Some configurations cause this directory to be emptied each time the system is rebooted.
/usr The /usr directory tree is likely the largest one on a Linux system. It contains all the programs and support files used by regular users.
/usr/bin /usr/bin contains the executable programs installed by your Linux distribution. It is not uncommon for this directory to hold thousands of programs.
/usr/lib The shared libraries for the programs in /usr/bin.
/usr/local The /usr/local tree is where programs that are not included with
your distribution but are intended for system-wide use are installed.
Programs compiled from source code are normally installed in /usr/
local/bin. On a newly installed Linux system, this tree exists, but it will
be empty until the system administrator puts something in it.
/usr/sbin Contains more system administration programs.
/usr/share /usr/share contains all the shared data used by programs in /usr/bin. This includes things such as default configuration files, icons, screen backgrounds, sound files, and so on.
/usr/share/doc Most packages installed on the system will include some kind of documentation. In /usr/share/doc, we will find documentation files organized by package.
/var With the exception of /tmp and /home, the directories we have looked at so far remain relatively static; that is, their contents don’t change. The /var directory tree is where data that is likely to change is stored. Various databases, spool files, user mail, and so forth, are located here.
/var/log /var/log contains log files, records of various system activity. These are important and should be monitored from time to time. The most useful ones are /var/log/messages and /var/log/syslog. Note that for security reasons on some systems, you must be the superuser to view log files.