FileSystem Hierarchy

The location of systems files (binaries, configurations, logs, devices, docs...) are typically a nightmare for a junior operator handling with Unix dialects. There are Unix standards, there's a Filesystem Hierarchy Standard, there's the distro maintainer's choice but, most of all you have tools useful to locate files positions: which, locate, whereis, whatis, apropos, find... In the apparent chaos of nested directories there's still coherence and login: /bin Essential user command binaries (for use by all users) /boot Static files of the boot loader /dev Device files /etc Host-specific system configuration /home User home directories (optional) /lib Essential shared libraries and kernel modules /media Mount point for removeable media /mnt Mount point for a temporarily mounted filesystem /opt Add-on application software packages /root Home directory for the root user (optional) /sbin System binaries /srv Data for services provided by this system /tmp Temporary files /proc Kernel and process information virtual filesystem     /var Variable files that change their size /usr Users commands and tools /var/account Process accounting logs (optional) /var/cache Application cache data /var/crash System crash dumps (optional) /var/lib Variable state information /var/lock Lock files /var/log Log files and directories /var/mail User mailbox files (optional) /var/opt Variable data for /opt /var/run Run-time variable data /var/spool Application spool data /var/tmp Temporary files preserved between system reboots /usr/X11R6 X Window System, Version 11 Release 6 (optional) /usr/bin Most user commands /usr/include Directory for standard include files /usr/lib Libraries for programming and packages /usr/local Local hierarchy /usr/sbin Non-essential standard system binaries /usr/share Architecture-independent data /usr/src Source code (optional) Source: http://www.pathname.com/fhs/