Interactive Commands

Normally SNOMAN is given a set of commands and is then left to get on with it. However, there are occasions when you need to be able to interrupt it. For example:-

• When running on-line with the dispatcher and without an event limit. SNOMAN won't end until an EOF is sent - which hopefully won't be for a long time!

• When running a long Monte Carlo if the system manager suddenly decides to take the machine down!

• When running with the histoscope option watching histograms accumulate and waiting for statistical fluctuations to die down.

Note that currently neither the dispatcher connection nor histoscope are in SNOMAN, although they will be very soon.

Commands can be passed to SNOMAN during execution if a command similar to:-

$interactive_commands my_file.cmd checkpoint=10

is included in its initial set of commands. At the checkpoint frequency (which is every 10 events in this example and defaults to every 100 if not supplied) SNOMAN looks for the specified file. If found it is opened, the commands processed, and then the file is deleted (so that it is not processed again). It takes time to check to see if the file exists, so reducing the checkpoint frequency increases the overhead, but reduces the time it takes to respond. SNOMAN must have write access to the file so that it can delete it. Directory searching is not applied; SNOMAN will not look on the prod or code directories for the file.

Currently the only command that will be obeyed at execution time is the QUIT command. Other command support may be added later.