Managing Directories

The structure of the HP 3000 file system traditionally allowed for a three-level hierarchy made up of accounts, groups, and files. With Release 4.5 of MPE/iX, the file system is now tree-strucured, or hierarchical. It uses directories, which are a special kind of file that points to other files and directories, to organize files in a logical manner.

The hierarchical directory structure has a common root, called the root directory and denoted by a slash (/). The root is the foundation of the HP 3000 directory structure since it contains all files and directories on the system. You can now put files under accounts in addition to being able to put them under groups, directories, and root.

To use pathnames

A pathname describes the route (or path) to a file. It is composed of the file name prefixed by any directory names. A slash (/) separates each part of a pathname. The maximum pathname length is 1023 characters, but other system limits can restrict pathname length. For example, the command interpreter limits the number of characters you can type in a command to 511 characters.

When the pathname begins at the root directory, it is called an absolute pathname. An absolute pathname is similar to a fully qualified MPE file name in that the names of all the components are listed. For example, the fully qualified MPE file name TDP.PUB.SYS translates to the absolute pathname /SYS/PUB/TDP.




	NOTE: File names using HFS syntax can use upper- and lower-case letters, and they are case sensitive. (For example, the file `My_file` is not the same as the file `my_file`.) You must specify all traditional (classic) MPE names in uppercase.

Other pathnames are relative to a process's current working directory, which is the directory where you are working. If you specify the name ./finance/expenses, MPE looks for a subdirectory called finance in your current working directory, then for a file called expenses in that directory.

Access to directories

Access to directories is controlled by Access Control Definitions, or ACDs. They include:

CD - Create directory entries
DD - Delete directory entries
RD - Read directory entries
TD - Traverse directory entries
RACD - Read ACD
NONE - No access

By default, directories allow Read ACD privilege to all users on the system (RACD:@.@). You assign or change directory ACDs using the ALTSEC command. To display directory ACDs, use the LISTFILE command. Refer to Chapter 9 for more information about ACDs and to the MPE/iX Commands Reference Manual, Vol. I (32650-90003) for detailed syntax and descriptions of ALTSEC and LISTFILE.

The root directory, accounts, and groups cannot be assigned ACDs. However, all users are granted access equivalent to read directory entries (RD) access and traverse directory entries (TD) access to root, all accounts, and all MPE groups.

You can create directories in any directory, group, or account to which you have CD access. You must have the following privileges to create directories:

Create directory entries (CD) access for the parent directory (or the equivalent, if the parent is a group)
Save files (SF) capability
Traverse directory entries (TD) access to the parent directory

To name directories

Directory names follow the same rules as file names. Directory names can include the special characters - (hyphen), _ (underscore), and . (dot); they can be uppercase, lowercase, or a combination of the two. The maximum name length for a directory created in the root directory, an MPE group, or an MPE account is 16 characters. Subdirectories of hierarchical directories can have names that are up to 255 characters long. They cannot begin with a hyphen.

The file names dot (.) and dot-dot (..) have special meaning. The special file name dot at the beginning of a relative pathname refers to the current working directory. The name dot-dot refers to the directory that is the next level up, also called the parent directory.

To work with directories

The table below lists the commands that are useful for managing directories on the HP 3000 and briefly defines each one. For more complete information and examples, refer to the MPE/iX Commands Reference Manual Volumes 1 and 2 (32650 -90003 and 32650-90364).

Table 5-1 Working with Directories

Command	What it Does
`NEWDIR`	Create a new directory. To create a new directory in the current working directory, enter `NEWDIR` and the directory name. To create a new directory in another group, enter `NEWDIR` followed by the full pathname of the group.
`LISTDIR`	A system-provided UDC that lists all directories and files in your current working directory. As the default, it does not list subdirectories that exist below any of the directories. To use `LISTDIR` to see any directories on the system, enter `LISTDIR dir@`.
`PURGEDIR`	Deletes a hierarchical directory. You cannot use `PURGEDIR` to delete an account, an MPE group, the root directory, or to directly delete a file. (`PURGEDIR` will delete files in a directory when you specify the `TREE` option.)
`CHDIR`	Moves from one directory to another. To return to your logon group (your initial working directory), enter `CHDIR` with no arguments. To move to the next level up, enter `CHDIR` followed by two dots (`..`). To move to another directory relative to the current directory, enter `CHDIR ./` followed by the directory name, for example, `CHDIR ./accounting`.
`SHOWVAR HPCWD`	Displays the current working directory. `HPCWD` is a CI variable that you can also include in the prompt.
`DISKUSE`	Displays the amount of disk space used by a directory. To see the amount of disk space used by the directory you specified and all of the files and directories below it, add a trailing slash (`/`) to the command line or use the `TREE` parameter. For example, `DISKUSE /finance/` or `DISKUSE /finance ;tree`.
`FINDDIR`	A system-provided UDC that search for a directory name (or pattern) starting at root.

Managing Directories

Technical documentation

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To use pathnames

Access to directories

To name directories

To work with directories