MPE/iX Shell and Utilities Reference Manual, Vol 2

Process Environment
Applications invoked directly from the MPE/iX CI inherit an empty environment list from the CI. MPE/iX
does not provide CI commands or system intrinsics to add environment variables to this list.
MPE/iX Shell and Utilities provides facilities to create and modify its environment list. When you
invoke the MPE/iX Shell using the –L option, the shell executes the commands in the system profile
(/etc/profile). These commands set up the default environment. The shell then executes com-
mands in your customized .profile file located in your home directory. Applications that rely upon
a meaningful environment list being inherited by a parent process should be invoked through
MPE/iX
Shell and Utilities.
Process Termination
On MPE/iX, if a parent process terminates without waiting for all of its child processes to terminate, the
resulting orphaned child processes are terminated immediately prior to termination of the parent pro-
cess. The implementation does not allow orphaned child processes to be adopted by a system process.
Your application should not rely upon orphaned child processes being adopted by a system process.
Additional Implementation Considerations
A user process cannot be a controlling process. Only system processes, such as the MPE/iX Command
Interpretor (CI) can be controlling processes.
The controlling terminal is not disassociated from the session of the calling process when the process
terminates. The controlling terminal is associated with the MPE/iX CI
session that invokes MPE/iX Shell
and Utilities. The controlling terminal is only disassociated when the MPE/iX session ends (when the
user logs off the system using the BYE command).
CPU time accounting information accrued by the
calling process is not made available to the parent process.
On
MPE/iX, a process’s real user ID, effective user
ID, and saved set-user-ID are always identical. In
addition, {SAVED_SET_IDS} is always defined.
TTY and Device Limitations
The current implementation of MPE/iX does not support a General Terminal Interface as defined in
POSIX.1. This has a number of consequences which affect how MPE/iX Shell and Utilities operates. The
affected areas are:
• Interrupting Processes
• End-of-File
• Direct Device Input/Output
• Configuring TTYs
• Reopening TTYs
A-18 MPE/iX Implementation Considerations