MIDAS commands fall into two categories:
the basic commands and all other application
commands. The basic commands are executed inside the MIDAS monitor, which
is the program you are interacting with.
All other commands are implemented by executing a MIDAS procedure which
runs one or more programs in a subprocess (child process).
During the time a command is being processed in the subprocess,
monitor is suspended until the corresponding program terminates in the
subprocess. Only then control is returned to the user. To stop a
command prematurely, type
Since process creation is much more expensive in VMS than in Unix these subprocesses are handled differently in VMS and Unix:
In VMS, the subprocess, named FORGRxy (with xy the MIDAS unit specified at start-up), is created at MIDAS initialisation time and kept alive until you exit from MIDAS via the command BYE.
In Unix, the child process is created each time the MIDAS command executes an application program. Upon termination of that program the child process dies. This also applies to commands of the host system - they are executed in a subshell.
Therefore, issuing `$ cd /elsewhere' inside MIDAS does not change your current directory permanently... You should use the MIDAS command CHANGE/DIRECTORY instead. See section 3.1 about the change-directory problem.
Some internal files are created when starting a MIDAS session in the directory specified via MID_WORK:. The most important ones are the keyword file and the logfile.
The keyword file is named FORGRxy.KEY (xy the MIDAS unit) and holds the keyword data base accessible by all programs running in the MIDAS environment.
The logfile is named FORGRxy.LOG and receives a log of all user input and all MIDAS output on the terminal (except HELP text, as explained before, and output from the host system). The logfile serves also as a ``fall back'' utility in case of system crash or other breakdown. In such a case the command PLAYBACK/LOG `logfile' may be used to regenerate the complete MIDAS session.
NoteIn order to use the playback facility, you have to rename the original logfile before restarting MIDAS via INMIDAS or inmidas. Remember that INMIDAS deletes old MIDAS logfiles unless you run in parallel mode .