Starting the MIDAS Monitor

In order to get properly initialised, MIDAS needs the following information

• the MIDAS user mode to work in: Parallel or Single User mode,  
  the default is Single User mode
• the MIDAS working directory for internal files and (optionally) private procedures:
  the default is a subdirectory midwork in your login directory,
  i.e. SYS$LOGIN:[MIDWORK] in VMS or $HOME/midwork in Unix.
  This directory does not have to be (or even should not be) the same directory where your data files are stored.

  
On a VMS system type SETMIDAS and follow the dialog if you want to change the defaults for the mode and the MIDAS work directory.
On a Unix/Linux system use the option -m <mid_work> to change the default working directory, and -p or -P to run MIDAS in parallel mode  when you start MIDAS via the command inmidas (see below). Two other variables are very important to MIDAS - MIDVERS, which holds the MIDAS version you use at your site, and MIDASHOME, the root directory for the MIDAS system code. These variables should have been set up correctly by your system manager when MIDAS was installed or use again SETMIDAS in VMS; for Unix these variables can again be chosen within the inmidas command. There are many more options for the inmidas command in Unix, which can be accessed interactively via the man page of inmidas (a complete Midas installation should also include the setting up of the man pages for inmidas, gomidas and helpmidas).
The detailed command description is as follows:

SYNOPSIS
   inmidas [ unit ] [ -h midashome ] [ -r midvers ] [ -d display ] 
   [ -m mid_work ] [ -p/-P/-nop ] [ -noh ] [ -j midas-command-line ] [ -help ]

   Without arguments, inmidas initiates a  MIDAS  session  with default
   definitions. Some of these definitions can be modified with arguments in
   the command line of inmidas or by environment variables. The arguments 
   in the command line override the corresponding environment variables.
OPTIONS
   inmidas has been configured by the Midas system manager at installation
   time to start a specific release of MIDAS. However, alternative releases
   can be specified using the command line arguments:

   -h midashome
      Home directory for MIDAS. Absolute pathname containing, at least, one
      release of MIDAS. It may also contain subdirectories for demo and 
      calibration data.
   -r midvers
      Release of MIDAS to be executed. It must be a subdirectory under
      midashome.
   -d display
      Specifies another X server for the display and  graphical MIDAS windows 
      NOTE: be aware of allowed access to a remote X server using the "xhost"
      command.
   -p/-P/-nop
      Options -p and -P set the MIDAS environment variable MIDOPTION to 
      PARALLEL while option  -nop sets it to NOPARALLEL (default: NOPARALLEL).
      In NOPARALLEL mode all intermediate MIDAS files in the MIDAS startup
      directory are deleted when starting MIDAS via inmidas.
      In PARALLEL mode no intermediate files are deleted, and this is
      necessary to run several MIDAS sessions with the same startup directory.
      With -P option and if unit is not given the system will select
      automatically one free unit for you. With -p option and no unit, the 
      user will be requested to enter one.
   unit 
      Unit to be associated to the MIDAS session (default: 00 only if MIDAS
      is working in NOPARALLEL mode). Valid values for this option are in the
      range (00, 01, ..., 99, xa, ..., zz) where numerical values indicate
      that the user is working in an X11 environment (DISPLAY environment 
      variable or argument -d should be given), and the others indicate an
      ASCII terminal.
   -m mid_work
      Specifies the MIDAS startup directory (default: $HOME/midwork).
   -noh 
      Starts MIDAS without clearing the terminal and without welcome message.
   -j midas-command-line
      midas-command-line will be executed in MIDAS as if it were the first
      command line typed in the MIDAS monitor.
      This option sets also the -noh  option.
      NOTE: midas-command-line should be typed between single quotes to be
      interpreted by inmidas as a single argument and to be passed to the
      MIDAS monitor as it is.
   -help
      Display this help page.

  
So, to start MIDAS, type INMIDAS on a VMS system or inmidas [arg1] ...  on a Unix system. This will initialize the MIDAS monitor as follows:

-

In VMS the logical name MID_WORK is assigned to the MIDAS working directory; in Unix the environment variable MID_WORK is set accordingly. If the working directory does not yet exist, it is created.
All internal files created by the MIDAS monitor will be stored in the MIDAS working directory. This is also the place to store your own login.prg  as well as all your other MIDAS procedures which you want to execute from any other directory.

-

In Single User mode, all MIDAS log- and keyfiles (FORGRxy.LOG, FORGRxy.KEY - where xy is the MIDAS unit described below) which exist in the MIDAS working directory as well as all MIDAS internal files are deleted.
In Parallel mode no files are deleted.

-

In VMS the user process is renamed to MIDASxy

-

In VMS and in parallel mode in Unix you will be asked to enter the identification of a MIDAS unit   as a two-character (case insensitive) string.
Units are in the range (00, 01, ..., 99, xa, ..., zz) where numerical values indicate that the user is working in an X11 environment (DISPLAY environment variable should be set), and the others define a MIDAS session with no image display capabilities.
So 23, xa, yf or Z3 will all be valid units. If you work in Parallel mode you have to use different MIDAS units for each session because the MIDAS unit is appended to the names of all MIDAS internal files.

  
On startup the current MIDAS version and patch level as well as the computer and operating system you are using are displayed together with a copyright notice. Then the prompt string

Midas 001>

appears on the terminal screen and you are ready to execute any of the available MIDAS commands.

The internal MIDAS files all reside in the MIDAS working directory MID_WORK, the data files are taken from the current working directory unless the complete file specification is given in the data file name.
Since MIDAS executes its applications in a child process (subprocess for VMS) which leaves no traces after termination, you cannot simply use the host command SET DEF (VMS) or cd (Unix) to change the working directory once you are in a MIDAS session. Instead, use the MIDAS command change/direc for that purpose.
Another possibility is to set the search path for your data files via the command
set/midas_system DPATH=directory. Use the MIDAS Help Utility for obtaining detailed information about these commands, e.g. HELP change/direc.   
MIDAS is a case insensitive system. That means, you can type your input with upper or lower case characters. There are, however, some pitfalls with respect to the data files that reside in the local file system. In VMS, the system automatically translates all file names to upper case, so LOLA.BDF and lola.bdf specify exactly the same file. In Unix, file names may be specified using lower and upper case, so LOLA.BDF and lola.bdf are two different files. The convention in MIDAS is to always use lower case file names (e.g. in tutorial procedures) to guarantee portability between VMS and Unix. Also, all default file types are specified in lower case, e.g. .bdf and .tbl for images and tables.

Note

All MIDAS commands in the following sections are printed with capital letters. This is just for reasons of readability, i.e., to highlight them. The commands could all be typed in lower case as well.