Starting McIDAS-X

To start a McIDAS-X session, start your X server (if necessary) then open a Unix shell and log on to your account. Then run the mcidas command in one of the three formats below.

Type: mcidas

Type: mcidas flags

Type: mcidas -config

The first command (mcidas) starts a McIDAS-X session using the current settings of the flags in the .mcidasrc file. The flags and their defaults are described in Configuring McIDAS-X Sessions with .mcidasrc. If McIDAS-X has not been previously run in your account, the .mcidasrc file does not exist. In this case, the mcidas command displays the McIDAS-X Configuration GUI (described below) and creates the .mcidasrc file. You can have the Configuration GUI appear each time you start a session with the mcidas command by adding the -config flag to your .mcidasrc file.

The second command (mcidas flags) is the same as the first, except that it includes adding one or more of the flags described in the Configuring McIDAS-X Sessions with .mcidasrc section to the command line. If you specify the -c or -f flags (for commands to run at startup and sets of frames to create at startup, respectively) on the command line they are run in addition to the -c and -f entries in the .mcidasrc file. All other flags (e.g., -e, -font, -graphicsColors, etc.) specified on the command line override their corresponding settings in the .mcidasrc file. Specifying flags on the command line with this flags option makes it easy to make one-time overrides or additions to settings in the .mcidasrc file. Without this option, you would have to change the settings in .mcidasrc, start a session with the mcidas command, then edit .mcidasrc again to change the settings back to their previous values.

The third command (mcidas -config) displays a McIDAS-X Configuration Graphical User Interface (GUI) window with sliders, checkboxes and text fields that are used to select values that override the settings of the corresponding flags in the .mcidasrc file. This Configuration GUI is designed to make one-time (for the current session only) configuration changes easier and less error-prone than other methods like changing flag settings in the .mcidasrc file or specifying the flags in the command line like the mcidas flags option above. The Configuration GUI also includes a "Save Settings" button to save the GUI settings in the .mcidasrc file. However, caution should be used with this option because it replaces the current .mcidasrc file so its settings are lost. To make recovery easier, the option first moves the current .mcidasrc to .mcidasrc.old before creating the new .mcidasrc with the GUI settings.

When a McIDAS-X session is started by any of the three methods above, the following then occur:

Two windows are displayed: the Text and Command Window and either the Image Window or the McIDAS-X Graphical User Interface, depending on the flags set in the .mcidasrc file. See the sections Entering and Editing Commands and Displaying Images and Graphics for more information about these windows.
Shared memory segments are created, as is a uniquely named temporary directory that stores session files. The temporary directory resides in $MCTMPDIR/.mctmp if the MCTMPDIR environment variable exists; otherwise it resides in $HOME/.mctmp. McIDAS-X also creates files such as FRAMED.001 in the temporary directory and adds the name of the temporary directory to MCPATH to make the files visible to the rest of McIDAS-X. The directory and its files are deleted when you end the McIDAS-X session.
The mcclean program is run to delete any inactive .mctmp directories it finds and remove any shared memory segments associated with the directories. Typically, there will not be any inactive temporary directories, but if a session ends in a catastrophic manner (e.g., with kill -9) the temporary directory may not be deleted.

Running multiple McIDAS-X sessions

Though not recommended because of possible file conflicts, you can run multiple McIDAS-X sessions from the same account. Multiple sessions include those started with the mcidas script and McIDAS-X commands run from the mcenv process or the Unix scheduler. For more information on using the mcenv process or Unix scripts, see Appendix H, Running Commands Outside a McIDAS-X Session. To differentiate between the files used for various sessions, each session stores many of its files in its own .mctmp subdirectory. When you run multiple sessions, the mccheck program warns you if there are files in a MCPATH directory that belong in a .mctmp subdirectory. The mccheck program only provides warnings when you run multiple sessions.

File conflicts are still possible because certain files and directories may be used by all sessions. For example, the default scheduler file, SKEDFILE, is stored in $HOME/mcidas/data (not a .mctmp directory) because it often contains entries to run in subsequent sessions. Therefore, if you are running multiple sessions and the scheduler is on (SKU command), anything scheduled to run in one session runs in all of them. If you need to set different schedulers in separate sessions under the same account, specify the -c 'SKED file' flag when starting each session. The file should be a different scheduler file for each session. Then use keyword FILE to specify the different scheduler files in the SKE and SKU commands.

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