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This section briefly introduces some of the new features of MPE/iX that you will encounter in this tutorial: Hierarchical file system (HFS)
New and enhanced commands
Hierarchical file system (HFS) | |
As of Release 4.5 and 5.0, 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®
or MS-DOS® 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'll learn more about HFS as you work through the
tutorial. But keep in mind, unless you're going to use a
new application that requires the new items (such as
directories), you can continue to use MPE as you have in the
past. 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 enhancements are compared to previous
releases in Table 1-1 “Where Accounts, Groups, Directories, & Files Can Be Located”. Table 1-1 Where Accounts, Groups, Directories, & Files Can Be Located | Location | Before Release 4.5 | Release 4.5 and After |
|---|
| Highest level | Accounts | Root | | Under root | Root not visible | Accounts, directories, or files | | Under accounts | Groups | Groups, directories, and files | | Under groups | Files | Directories or files | | Under directories | Directories not available | Directories or files |
Figure 1-1 “MPE/iX File System Example” 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. Figure 1-1 MPE/iX File System Example
![[MPE/iX File System Example]](img/208001.gif)
HFS file names | |
MPE/iX now allows you to assign longer file names
than in previous versions of MPE/iX. Table 1-2 “Maximum Lengths of Account, Group, Directory, and File Names” summarizes
name lengths for accounts, groups, directories, and files previous to Release 4.5 or greater. Table 1-2 Maximum Lengths of Account, Group, Directory, and File Names | Type | MPE Syntax | HFS Syntax |
|---|
| Account name | 8 uppercase characters | 8 uppercase characters | | Group name | 8 uppercase characters | 8 uppercase characters | | Directory name | Not available | 16 mixed case characters if directly under root, account, or a group. Up to 255 characters elsewhere. | | File name | 8 uppercase characters | 16 mixed case characters if directly under root, account, or a group. Up to 255 characters elsewhere.
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See "Summary of MPE/iX syntax features" in Chapter 2 for additional information about name lengths. HFS syntax | |
Table 1-3 “Syntax Summary” 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 | Item | MPE Syntax | HFS Syntax |
|---|
| Specify file name | No special beginning character required: FILE.GRP.ACCT | Name must be preceded by a ./ (dot slash)
or / (slash): /ACCT or ./dir1 | | Name separators | . (period); / separates lockwords | /(slash) | | Way of specifying files | Bottom up: FILE.GRP.ACCT | Top down: /ACCT/GRP/FILE | | Case sensitivity | Not case sensitive; all characters are shifted to uppercase | Case sensitive: /DIR/FILE1 and /DIR/file1 are two different files | | Special characters | Only alphanumeric characters | Alphanumeric, - (hyphen), . (dot), and _ (underscore) are allowed | | First character | Must be alphabetic | Can be alphanumeric, _ (underscore), or . (dot) but not - (hyphen)
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New commands | |
ALTFILE alters a file's attributes such as UID and GID of a file, directory, and MPE group or account (except that
the GID may not be altered for MPE groups or accounts).
CHDIR lets you move your CWD (much like changing
groups).
DISKUSE displays disk space used by accounts, groups,
and directories, that is, all items in the hierarchical file
system. (The REPORT command still provides disk space
accounting for accounts and groups. It just won't include
detailed information about directories below accounts, and
it does not report on directory structures directly below
the root.)
NEWDIR lets you create directories. After creating
directories, you can use the ALTSEC command if you want
to grant access to other users.
NEWLINK creates a symbolic link to a file, group,
account, or directory.
PURGEDIR is for deleting directories.
PURGELINK is for removing a link.
SETCLOCK alters the system time or system time zone.
SHOWCLOCK displays information about the system date and time.
Enhanced commands | |
FILE declares the file attributes to be used when a
file is opened. This declaration, informally known as a
file equation, may be used to override programmatic or
system default file specifications. With the addition of
shared parameters from the NS3000/XL AdvanceNet subsystem,
the declaration may specify a formal file designator that
may be used to access a remote file or device in a
subsequent command or intrinsic.
LISTF (UDC) executes the LISTFILE
command to list descriptions of one or more disk files.
LISTFILE allows you to display directories
and all HFS file names.
PURGE deletes a file from the system.
RESTORE returns files that have been stored on magnetic tape to the system.
RUN executes a prepared or linked program. The only
required parameter is progfile. If you specify any
other parameters, they will override the default parameters
that the creator of the program established, but only for
that particular execution of the program.
SAVE command saves a file from the temporary domain to the permanent domain.
SHOWDEV reports the status of input/output devices.
SHOWPROC displays information about one or more
processes.
STORE copies disk files onto a magnetic tape. Files copied to tape with the STORE command can be recovered with the RESTORE command.
VSTORE verifies that the data on a backup media are valid and reports errors incurred by STORE when writing the tape. VSTORE only applies to NMSTORE tapes created in native mode. It does not work on tapes created in compatibility mode.
Symbolic Links | |
Symbolic linking is the concept of indirectly referring
(pointing) to another file on the system. This concept is
similar to MPE/iX file equations. A symbolic link is a type
of file that contains another path name. It is a permanent
file in the system directory. Symbolic links can be
created, removed, renamed, and archived. |
