Command queueing tools by Dan Marcus.
Set ARC_TOOLS in each script to a directory where the queue and
logs will be written. Then use:
arc-queue command arg ...
to queue a command, and:
to run the commands in the queue.
Normally arc-queue is called from pipeline/bin/schedule or
pipeline/bin/XnatPipelineLauncher (to catch the auto-run pipelines
as well), and arc-qrunner is called by a cron job.
See the comments at the head of each file for more information.