HP 3000 Manuals HP 3000 Manuals
Hierarchical file system (HFS)
As of Release 4.5, the MPE/iX file system is hierarchical (tree
structured) and can contain files at many different levels. This
organization provides a special kind of file called a directory. Instead
of holding data, directories contain lists of files and pointers to those
files. A directory can also contain other directories. This
organization is similar to the file systems on UNIX(R) or MS-DOS(R)
systems.
The new file organization still includes the familiar accounts, groups,
and users. The hierarchical file system (called HFS, for short) extends
the traditional MPE file system features so the operating system is more
flexible.
You're used to referring to files, groups, and accounts using the
traditional MPE syntax: FILE1.PUB.SYS. You can still use MPE syntax.
You can also make use of a new syntax called HFS syntax, which looks like
this: /SYS/PUB/FILE1.
The MPE/iX Release 4.5 enhancements are compared to previous releases in
Table 1-1 .
Table 1-1. Where Accounts, Groups, Directories, and Files Can Be Located
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| | | |
| Location | Before Release 4.5 | Release 4.5 and After |
| | | |
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| | | |
| Highest level | Accounts | Root |
| | | |
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| | | |
| Under root | Root not visible | Accounts, directories, or |
| | | files |
| | | |
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| | | |
| Under accounts | Groups | Groups* |
| | | |
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| | | |
| Under groups | Files | Directories or files |
| | | |
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| | | |
| Under directories | Directories not available | Directories or files |
| | | |
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| |
| * This is an initial release restriction that may be lifted in a future release. |
| |
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shows how you can organize files, accounts, groups, and directories in
the file system. Notice that accounts, directories, groups, and files
all connect back to one directory designated by a "/" (slash). This is
referred to as the root or the root directory.
![[]](../../pic3k/M013652/FFN63c50.gif)
Figure 1-4. MPE/iX File System Example
HFS file names
MPE/iX Release 4.5 allows you to assign longer file names than in
previous versions of MPE/iX. Table 1-2 summarizes name lengths for
accounts, groups, directories, and files previous to Release 4.5 and
after Release 4.5.
Table 1-2. Maximum Lengths of Account, Group, Directory, and File Names
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| | | |
| Type | MPE Syntax | HFS Syntax |
| | | |
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| | | |
| Account name | 8 uppercase characters | 8 uppercase characters |
| | | |
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| | | |
| Group name | 8 uppercase characters | 8 uppercase characters |
| | | |
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| | | |
| Directory name | Not available | 16 mixed case characters (if directly |
| | | under root or directly under a |
| | | group). |
| | | Up to 255 characters (elsewhere). |
| | | |
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| | | |
| File name | 8 uppercase characters | 16 mixed case characters (if directly |
| | | under root or directly under a |
| | | group). |
| | | Up to 255 characters (elsewhere). |
| | | |
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HFS syntax
Table 1-3 summarizes some of the syntax enhancements introduced by
the MPE hierarchical file system. The syntax that you are used to still
works for files in groups and accounts. So to use HFS syntax, you must
precede file and directory names with ./ or /. Otherwise, MPE/iX treats
the names using traditional MPE syntax rules.
This manual refers to files that are named using HFS syntax as HFS files.
Table 1-3. Syntax Summary
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| | | |
| Item | MPE Syntax | HFS Syntax |
| | | |
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| | | |
| Specify file name | No special beginning | Name must be preceded by a ./ (dot |
| | character required: | slash) or / (slash): |
| | FILE.GRP.ACCT | /ACCT or ./dir1 |
| | | |
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| | | |
| Name separators | . (period); / separates | / (slash) |
| | lockwords | |
| | | |
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| | | |
| Way of specifying files | Bottom up: FILE.GRP.ACCT | Top down: |
| | | /ACCT/GRP/FILE |
| | | |
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| | | |
| Case sensitivity | Not case sensitive; all | Case sensitive: /DIR/FILE1 and |
| | characters are shifted to | /DIR/file1 are two different files |
| | uppercase | |
| | | |
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| | | |
| Special characters | Only alphanumeric | Alphanumeric, - (hyphen), . (dot), |
| | characters | and _ (underscore) are allowed |
| | | |
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| | | |
| First character | Must be alphabetic | Can be alphanumeric, _ (underscore), |
| | | or . (dot) but not - (hyphen) |
| | | |
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