MPE/iX Shell and Utilities Reference Manual, Vol 2

Process Management
This section provides an overview of implementation considerations you must understand when creat-
ing and managing processes as they are implemented in MPE/iX
Shell and Utilities.
The implementation and behavior of processes created through MPE/iX Shell and Utilities conform in
most respects to the POSIX.1 standard. In most cases, underlying MPE/iX process features are transparent
to MPE/iX
Shell and Utilities; however, there are some MPE/iX features outside the scope of the POSIX.1
standard that cannot be hidden from your application. You must take these additional implementation
features into account when creating and managing processes through
MPE/iX Shell and Utilities.
Creating a New Process
When using MPE/iX Shell and Utilities to create and execute processes, the executable file must have an
MPE/iX
file code of NMPRG. Any attempt to execute a file with a name that does not conform to this
rule results in a system error (see syserror(3)).
An executable file that is compiled and linked using the c89 command (available through MPE/iX Shell
and Utilities) always creates an executable file with an
MPE/iX file code of NMPRG.
To determine whether a file has an MPE/iX file code of NMPRG, you must use the
MPE/iX CI command
LISTFILE. For more information about using the LISTFILE command, refer to the MPE/iX Refer-
ence Supplement (32650-90353).
MPE/iX Process Handling Capability
By default, MPE/iX restricts the user’s ability to spawn multiple processes under the MPE/iX
Command
Interpretor (CI). The MPE/iX process handling (PH) capability allows the creation of multiple processes.
The executable file must be linked with
PH capability. The c89 command available through the MPE/iX
Shell automatically assigns PH capability to files at link time.
Inherited Process Attributes
Because processes created through MPE/iX Shell and Utilities reside in an MPE/iX process environment,
certain MPE/iX process attributes are inherited by the new process. These MPE/iX process attributes
remain transparent in a POSIX environment.
For example, a new process inherits the following MPE/iX process attributes:
• Process priority
• Capabilities
• Stack size
• Heap size
Also, the child process does not inherit some MPE/iX process attributes (those not defined by the POSIX.1
standard). These MPE/iX process attributes remain transparent in a POSIX environment.
MPE/iX Implementation Considerations A-17