MPE/iX Shell and Utilities Reference Manual, Vol 2

Files
This section provides an overview of implementation considerations you should understand when
creating, accessing, and managing files through MPE/iX Shell and Utilities.
POSIX File Types
The following table lists the five file types defined in the POSIX.1 standard with their equivalent imple-
mentations on MPE/iX
:
POSIX File Type MPE/iX File Type
Byte stream file, used to refer to a MPE/iX standard ASCII
disk file with a record format of byte stream.
Regular file
Directory file, used to refer to an MPE/iX directory file.Directory special file
Block device special file Not implemented on MPE/iX
Table A-4: MPE/iX Implementations of
POSIX File Types
MPE/iX supports a special file type that has a record format of byte stream to reproduce the file behavior
defined in the POSIX.1 standard.
You can find additional information about MPE/iX byte stream files in New Features of MPE/iX: Using
the Hierarchical File System (32650-90351).
Refer to the section Directories for implementation details of
MPE/iX directory files.
Creating and Opening Files
The user ID (UID) of a newly created file is set to the UID of the creator of the file. The group
ID (GID)of
a newly created file is set to the GID of the directory (the parent directory) in which the file is created.
Directory Restrictions
A file created directly under the root directory, under an MPE/iX account, or under an MPE/iX group can-
not have a file name that exceeds 16 characters in length. Attempts to create a file with a name exceed-
ing 16 characters in length directly under the root directory, a group, or an account results in a system
error (see syserror(3)).
Input/Output Considerations
The following sections describe implementation details associated with data transfer through MPE/iX
Shell and Utilities.
The
POSIX.1 standard does not recognize a file limit with a regular file. The size is defined by the user.
MPE/iX, however, provides two facilities for limiting the amount of disk space a user can have for files:
MPE/iX Implementation Considerations A-7