What Is the Command Interpreter?

The CI is an executable program that acts as an interface between the user and MPE/iX.

It consists of two parts: a centralized scanner/parser that scans a command string for valid syntax, and an interpreter that invokes the appropriate command executor based on command input.

The scanner/parser analyzes the command string for proper syntax. If the syntax is incorrect, it is returned for correction. If correct, the command string is passed to the interpreter portion of the CI.

The interpreter identifies the command as a user-defined command, predefined system command, program file, or command file. It then invokes the appropriate procedure to process the command or to run the specified program file or command file.

The CI and many of its commands operate on HFS (hierarchical file system) file names and directories. In addition, several commands are dedicated to operations on HFS files and directories. Refer to New Features of MPE/iX: Using The Hierarchical File System (32650-90351) and to MPE/iX Commands Reference Manual (32650-90003).

In addition, a CM (compatibility mode) command (plus its parameters and objects) can consist of 253 characters for commands invoking a relative pathname; or it can consist of as many as 255 characters for commands invoking an absolute path name. The maximum size for native mode commands is 511 characters, less the length of the command and and other parameters.

	NOTE: If a POSIX (HFS) object is directly under root or an MPE group, its name length is reduced to a maximum of 16 characters.