lease - get a lease on the node's communications link

lease
lease -establish [<time>]       [nodeHost]
lease -renew <leaseID> [<time>] [nodeHost]
lease -terminate <leaseID>      [nodeHost]

lease is a utility to take out and/or manage a lease on the node's communications link.  Leasing is a facility to allow anyone to declare that they need to use the communications link to shore for a given period of time (specified in seconds).  Any number of people/programs/etc can separately take out a lease.  As long as any lease is still valid, the communications link will stay active and the CPU will remain awake.  When the time that you specified for your lease has elapsed (assuming you haven't renewed the lease), the lease expires.  If it was the last lease to be active, the communications link will then go down.

There are three operations that can be performed by lease: "-establish", "-renew", and "-terminate".  The default operation (if you don't specify any of the above) is "-establish", which establishes a new lease.  This returns a new leaseID, which is simply an integer that you can use to reference this lease for further operations.

"lease -renew <leaseID> <time>" will renew the lease for <time> seconds.

"lease -terminate <leaseID>" terminates the lease (makes it immediately invalid).

The defaults for lease are:
-establish
<time> = 600 (seconds, which is 10 minutes)
[nodeHost] = localhost

Thus, if you issue the simple command "lease", you get
lease -establish 600 localhost

The command-line parser is very forgiving -- parameters can be in almost any order.  The only constraint is that for "-renew", <leaseID> must occur before <time>.  Anything that begins with "//" or an alphabetic character is assumed to be the nodeHost.
 

Be aware that if you hold the comms line open with a long lease, not only will you cost the system a lot of power, but data will not be downloaded to the portal in the interim.  That's because the trigger for downloading the data is bringing up the comms link.  If you have a lease, the link doesn't go down during that time, and thus doesn't need to be brought back up.

This is not a bug in lease, but is inherent in the design of the SIAM software.

ENVIRONMENT

The following environment variables must be set:

• JAVA - name of the JVM. E.g. on a Sidearm, JAVA should be set to j9. On a workstation with Sun's Java installed, JAVA could be set to java.
• SIAM_HOME - top of the SIAM directory tree
• SIAM_CLASSPATH - on a Sidearm, SIAM_CLASSPATH should be set to $JAVA_HOME/lib/jclMax/classes.zip:$JAVA_HOME/lib/prsnlmot.jar:$JAVA_HOME/lib/RXTXcomm.jar:$SIAM_HOME/classes.  On X86 system, SIAM_CLASSPATH should be set to $SIAM_HOME/classes

SEE ALSO

Historically, some people have used lease when they don't need the communications port, but simply for its side-effect of keeping the CPU awake.  Please use  cpuAwake instead.