MPE/iX Shell and Utilities Reference Manual, Vol 2

Constant Default Description and Implementation Details
Action
Job Control Signals
Ignore the
signal
Child process stopped or terminated. Required for
POSIX.1 conformance.
SIGCHLD
Continue if
stopped;
otherwise,
ignore
Continue if stopped. This signal is never generated
by the system. Required for POSIX.1 conformance.
SIGCONT
Stop the
process
Stop signal (cannot be caught or ignored). If an
application attempts to change the default action
associated with SIGSTOP, the attempt is ignored
without error. This signal is never generated by the
system. Required for
POSIX.1 conformance.
SIGSTOP
Stop the
process
Interactive stop signal. Because job control is not
implemented, your application should not rely upon
the generation of this signal by the system. Required
for
POSIX.1 conformance.
SIGTSTP
Stop the
process
Read from the controlling terminal attempted by a
member of a background process group. Because job
control is not implemented, your application should
not rely upon the generation of this signal by the sys-
tem. Required for
POSIX.1 conformance.
SIGTTIN
Stop the
process
Write to the controlling terminal attempted by a
member of a background process group. Because job
control is not implemented, your application should
not rely upon the generation of this signal by the sys-
tem. Required for
POSIX
.1 conformance.
SIGTTOU
Table A-5: Signals Required by POSIX.1 (continued)
Additional Implementation Considerations
On MPE/iX, signals cannot be delivered to a process while that process is executing system code. The
signal remains pending until control returns to the calling process. A sending process cannot rely on
timely delivery of a signal if the target process is executing system code.
For example, if a signal is generated for a process when the process is reading from or writing to a file,
the signal remains pending until after a successful transfer of data or until an error is encountered.
When using the kill command, the value -1 is not valid when specifying a target process. If you
specify -1 as a target process, kill returns a system error (see syserr(3)).
A-16 MPE/iX Implementation Considerations