First pass at a working version of the script.

README

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+This is a wrapper for cron jobs which implements common housekeeping tasks.
+
+- Failure suppression
+- Overlap protection
+
+Failure Suppression
+-------------------
+
+If enabled cronwrap will suppress non-zero exit values and output unless the
+job exceeds the specified number of consecutive failures. This is useful for
+jobs that might fail occasionally due to extenuating circumstances but for
+which the occasional failure is not a big deal as long as it the job starts
+running successfully again soon.
+
+Overlap Protection
+------------------
+
+If enabled cronwrap will not start multiple simultaneous copies of job. For
+example, you have a job that runs once an hour and usually completes in a
+minute. However, there's a chance it will get stuck and take more than an hour
+or even hang forever. You might not want cron to start another copy of the job
+while the previous job is still running.
+