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The file reference can be either in MPE/iX or POSIX namespace.

The MPE file domain consists of MPE accounts, MPE groups and files which reside in these groups.accounts. The MPE file domain is a 3 level Hierarchical File System (HFS).

The POSIX file domain is considered a superset of the MPE file domain.

The POSIX file domain consists of a root (/) and POSIX directories, which can contain additional directories or files. The POSIX file domain is a multi-level Hierarchical File System.

POSIX is implemented on MPE/iX in such a manor that it is a superset of MPE. MPE accounts are now under the POSIX root (/) and are treated as special directories; likewise MPE groups are located under accounts and again are treated as special directories.

As a result of this implementation, files in the MPE file domain can be accessed by MPE applications; and, since the POSIX file domain is a superset of the MPE file domain, POSIX applications can also access these files. In general MPE applications cannot access files in the POSIX file domain unless the application, or the file procedures it calls, are specifically coded to do so.

MPE/iX Namespace

If the file reference does not begin with a dot or a slash, it is parsed according to the MPE/iX syntax and has the following format: 

  filename [/lockword] [.groupname [.acctname]]
MPE/iX names must contain from one to eight alphanumeric characters, beginning with an alphabetic character. If acctname is specified, you must create directory (CD) access to the target group in the account. The default groupname and acctname are the logon group and account. Filenames in MPE name space are not case sensitive, and are all shifted to uppercase.

POSIX Namespace

If the file reference begins with a dot (.) or a slash (/), it is parsed according to the POSIX syntax. In this case the file reference can be ./Directory 1/Directory 2/Directory 3/... .

The following syntax rules apply:

  • File names are not shifted to uppercase.

  • File names can be up to 254 characters in length for absolute pathnames, and 253 characters for relative pathnames.

  • File names can begin with, and contain, any of the following characters: 

    
      a—z      A—Z,      0—9,      _,      .

  • File names can contain (but not begin with) a dash (-).

  • File names are of the form (path/filename) where the path/filename combination can have a maximum of 255 characters.

For more information, refer to the New Features of MPE/iX: Using The Hierarchical File System Reference Manual for accepted syntax of file names and directories.

Sample File Name MPE File Name Space POSIX File Name Space
FILENAMEFILENAMEFILENAME
filenameFILENAMEfilename
longfilenameInvalid MPE file namelongfilename
Read_MeInvalid MPE file nameRead_Me

NOTE: The file identifiers "./FILENAME" and "./filename" refer to two different files in the POSIX name space since character case is accepted in the POSIX name space.

Example 1:

Files in the MPE file domain in PUB.SYS (MPE syntax) are also viewed as being a part of the POSIX file domain in /SYS/PUB/ (POSIX syntax). 

  :listf log@.pub.sys
  FILENAME
  LOG      LOG0112      LOG0113
or 

  :listfile /SYS/PUB/LOG@
  PATH= /SYS/PUB
  LOG      LOG0112      LOG0113

Example 2:

Files in the POSIX file domain in "/SYS/PUB/directory1/directory2/" (POSIX syntax) are outside of the MPE file domain. 

  :listf /SYS/PUB/directory1/directory2/
File name missing. (CIERR 531) 

  :listfile /SYS/PUB/directory1/directory2
  PATH= /SYS/PUB/directory1/
  directory2/
  PATH = /SYS/PUB/directory1/directory2/
  TESTDATA
NOTE: The MPE listf command executes against files in the MPE file domain. The MPE command listfile created for POSIX executes against files in both the MPE and POSIX file domains.



Appendix A MPE/iX and POSIX Differences

Working With Directories