The cbiviewer command-line arguments.

There are 4 sets of alternate command line options depending on what one is trying to achieve.

To just start up the viewer without specifying an initial configuration and without specifying a source of data to be displayed, type:
```
 cbiviewer
```
To start up the viewer with a specified configuration file, but without specifying a source of data, type:
```
 cbiviewer [options] configure configuration_file
```
To start up the viewer, optionally with a given configuration file, and have it receive live data from the control program, type:
```
 cbiviewer [options] monitor hostname [configuration_file]
```
To start up the viewer with a specified configuration file, and have it read data from the archive, type:
```
 cbiviewer [options] read start_time end_time configuration_file
```
Note that if the start time is specified as an empty string (""), the earliest time available in the archive is substituted. Similarly if the end-time is given as an empty string, the latest time available in the archive is substituted.
To have the viewer start by reading to the end of the archive data, then switch to receiving live monitor data from the control program, specify the name of the control program computer in the end_time field. For example:
```
  cbiviewer read 4-Nov-1999:23:30 vega ~cbi/conf/observe.cnf
```
would read all data from 4-nov-1999 at 23:30 UTC to the end of the archived data. Then it would attempt to connect to the control program on a computer called vega. This allows one to prime one's live monitoring plots with preceding data from the archive.

Options

All of the above alternatives for starting the viewer program can take a number of optional arguments, some of them having values, while others are just flags.

-help: Print this help information.
-arcdir directory: This can be used to specify a different directory in which to search for archive files. If this isn't specified, archive files are looked for in the directory named by the CBI_ARC_DIR environment variable.
-bufsize number of elements: This sets the size of the buffer which is used to maintain plotted data in memory. The size is specified as the number of register values that can be stored. By default this is 500000. These 500000 elements are then divided up between all of the registers that are being plotted. For example, if one were to have 4 graphs, each one displaying a single register then these 4 registers plus the x-axis register constitute 5 registers to be stored per snapshot received from the control program. Thus one could display 100000 points per graph. After this point, the oldest data is deleted to make way for new data as it arrives. So, clearly the larger you make this buffer, the more data you will be able to display. Unfortunately enlarging the buffer doesn't come without consequences. Excessive memory usage can make the computer thrash when you replot a graph, and replotting or zooming a graph with a lot of points can be painfully slow.
-calfile filename: By default calibration data are read from $CBI_DIR/conf/cal. This flag can be used to specify a different calibration file.

Environment variables

The following environment variables effect the operation of the viewer:

CBI_DIR: This variable should contain the directory at the top of the CBI directory tree. Currently this is only used to set the default calibration file to $CBI_ARC_DIR/conf/cal.
CBI_ARC_DIR: This optional variable specifies the default directory in which to search for archive files. If it isn't set to anything, the current working directory is assumed unless the -arcdir flag is presented.

Martin Shepherd (4-Nov-1999)