Hierarchical file systems Version 3.0 and higher of 1616/OS store their files in a hierarchical or tree structure. With large capacity disks, the keeping of all a disk’s files within one directory becomes unmanageable; sub-directories are used to categorise disk files, as explained below. Directories A disk directory is a list of information about a number of disk files. Each section in the list is called a ‘directory entry’. A directory entry may describe either a file, or another directory. By putting directories within directories, a tree-structured file system is built.
Because the structure is like a tree, the main directory is generally known as the root directory, and for historic reasons is shown as ‘ / (Experienced computer users should note that MS-DOS uses a backwards slash ‘\’ instead.) There is no limit to the number of files or directories that can be contained in the root directory, or any other directory. When a directory is first made, it contains space for 16 entries. It expands by an extra 16 entries as required. If it contains too many entries, it tends to slow down disk access. However you can make other named directories, each of which also can contain multiple names. Each of these directories can also contain named directories, and so on!
In general, directories that contain more than about 50 to 100 files tend to get unwieldy. You can create a new directory using the mkdir pathname [pathname ...] command. You should try to make the ‘pathname’ both meaningful, and short (if you make it too long, you will get tired of typing it). You can create several new directories simultaneously with this command. You can move into the new directory using the cd pathname’ command. You will notice that the command prompt will change from something like /f0/bin to show which sub directory you are now in. If you now create another directory using mkdir , and move to it using cd , your command prompt will show both directory names.
You can suppress the display of the directory path by using the option command (see Reference section of this manual for details). You can move back to the previous, or parent, directory using ‘ cd .. ’, and continue doing this until you reach the root directory. You can also reach the root directory directly, by typing the shortcut cd / . The directory you are currently in is, for historic reasons, known as ‘ . Files and Directories User Tutorial Manual Page 35