Filesystem Hierarchy Standard

Sometimes it is difficult to grasp directory structure in Linux/Ubuntu without referring to Filesystem Hierarchy Standard, FHS, which defines directory structure and directory contents in Linux distributions.

In the FHS, all files and directories appear under the root directory /, even if they are physically on different disks or devices.

Binaries and libraries

System scope

• /bin For binaries usable before the /usr partition is mounted. This is used for trivial binaries used in the very early boot stage or ones that you need to have available in booting single-user mode.For example: cat, ls, cp.

• /sbin System binaries (e.g., fsck, init, route), available for root

• /lib Libraries for the binaries in /bin and /sbin.

User scope

• /usr/bin Command binaries (not needed in single-user mode); for all users.

• /usr/lib Libraries for the binaries in /usr/bin and /usr/sbin.

• /usr/local It has subdirectories (e.g., bin, lib, share) for local data specifically for to the host.

• /usr/sbin Non-essential system binaries (e.g., daemons for various network services).

Variable files

• /var Files such as logs, spool files, and temporary e-mail files, whose content are continually changed during operation of the system.

• /var/cache Application cache data locally generated as during I/O or calculation.

• /var/lib State information. Persistent data modified by programs as they run (e.g., databases, packaging system metadata, etc.).

• /var/lock Lock files. Files keeping track of resources currently in use.

• /var/log Log files.

• /var/opt Variable data from add-on packages that are stored in /opt.

• /var/tmp Temporary files to be preserved between reboots.

Others

• / Primary hierarchy root and root directory of the entire file system hierarchy.

• /boot Boot loader files (e.g., kernels, initrd).
• /dev Device files (e.g., /dev/null, /dev/disk0, /dev/sda1, /dev/tty, /dev/random).
• /etc Host-specific system-wide configuration files.
• /etc/opt Configuration files for add-on packages that are stored in /opt.

• /home Users’ home directories, containing saved files, personal settings, etc.

• /media Mount points for removable media such as CD-ROMs (appeared in FHS-2.3 in 2004).

• /opt Add-on application software packages.

• /root Home directory for the root user.

• /sys Contains information about devices, drivers, and some kernel features.

• /tmp Directory for temporary files (see also /var/tmp), and they are not preserved between system reboots and can be size-restricted.

• /usr Secondary hierarchy for read-only user data; contains the majority of (multi-)user utilities and applications. Should be shareable and read-only.

• /usr/include Standard include files.

Where should I put my script ?

The answer is none of the above. I suggest to use /usr/local/bin to make available for system-wide unless I use ~/bin for user scoped script. The script and its data are located under personal home directory.

Under /usr/local there are potentially more subdirectories to accommodate libraries or data, e.g., /usr/local/bin, /usr/local/lib, /usr/local/share.