Unix Lesson 5: Directory Structure

In lesson 1 we talked about the filesystem and how these things operate. Unix has a set of pre-determined places on the filesystem to put stuff. This "schema", or pattern in which the files are laid out, is a standard amongst Unix systems, to varying degrees of conformance between them. This lesson goes into those directories, and their purpose.

It's not important to memorize these. Just become familiar with them so you know where to look when confused. Also, there are lots of differences between versions of Unix. None are created alike.

/etc: this is where most of the configuration for your operating system goes.
/bin: "user" binaries such as ls, cat, and so on go here. "Binary" in this case is another word for "program".
/sbin: "system" binaries such as administrative tools.
/usr: Other parts of the system that are non-critical to functioning go here.
/usr/bin, /usr/sbin: binaries of a non-critical nature. User applications and administrator applications, like your web browser, go here.
/usr/local: Self-installed programs and configuration. See /usr/local/bin, /usr/local/sbin, /usr/local/etc, etc.
/lib: Shared libraries, which contain code used by many programs.
/mnt: Temporary place for mounting disks, such as thumb drives.
/tmp: Temporary storage. In some cases this is just in RAM, other times it is on disk, but cleared on reboot.
/dev: Device files. These correspond to hardware devices, as well as some system functions provided by the core of the operating system, called the "kernel".
/home: Home directory for user accounts. This is your personal storage space. The directory structure is /home/<username>.
/var: variable data that is not temporary. For example, local email (yes, all Unix systems all have email support) is stored in /var/spool/mail, and log files for the operating system are stored in /var/log.

As you can see, there are quite a few, and this is not an exhaustive list. It pays to learn your system.

Assignment:

You can count the number of files and directories in a directory like so:

ls -1 <directory name> | wc -l

How many files & directories do you have in /bin? How about /dev?