jobber examples: repeating tasks

jobber can repeat tasks that were already executed. The example shows how all tasks that failed, i.e. that ended with non-zero exit status, can be repeated:

• The retry action puts all failed tasks back into the queue.
• The print:queued action is employed to show the task queue. The queue is empty before retry an contains the tasks that failed afterwards.

shell$ cat task.list
sleep 1; echo '--task-1--'; exit 0
sleep 1; echo '--task-2--'; exit 1
sleep 1; echo '--task-3--'; exit 0
sleep 1; echo '--task-4--'; exit 1
sleep 1; echo '--task-5--'; exit 0
sleep 1; echo '--task-6--'; exit 1
sleep 1; echo '--task-7--'; exit 0
sleep 1; echo '--task-8--'; exit 1
shell$ jobber task.list init
[2022-04-06T12:12:01] appended 8 tasks
shell$ jobber task.list 8 
[2022-04-06T12:12:01] 1.1 task.worker: sleep 1; echo '--task-1--'; exit 0
--task-1--
[2022-04-06T12:12:02] 1.1 exit status: 0
[2022-04-06T12:12:02] 2.2 task.worker: sleep 1; echo '--task-2--'; exit 1
--task-2--
[2022-04-06T12:12:03] 2.2 exit status: 1
[2022-04-06T12:12:03] 3.3 task.worker: sleep 1; echo '--task-3--'; exit 0
--task-3--
[2022-04-06T12:12:04] 3.3 exit status: 0
[2022-04-06T12:12:04] 4.4 task.worker: sleep 1; echo '--task-4--'; exit 1
--task-4--
[2022-04-06T12:12:05] 4.4 exit status: 1
[2022-04-06T12:12:05] 5.5 task.worker: sleep 1; echo '--task-5--'; exit 0
--task-5--
[2022-04-06T12:12:06] 5.5 exit status: 0
[2022-04-06T12:12:06] 6.6 task.worker: sleep 1; echo '--task-6--'; exit 1
--task-6--
[2022-04-06T12:12:07] 6.6 exit status: 1
[2022-04-06T12:12:07] 7.7 task.worker: sleep 1; echo '--task-7--'; exit 0
--task-7--
[2022-04-06T12:12:08] 7.7 exit status: 0
[2022-04-06T12:12:08] 8.8 task.worker: sleep 1; echo '--task-8--'; exit 1
--task-8--
[2022-04-06T12:12:09] 8.8 exit status: 1
shell$ jobber task.list print:queued
#!/bin/bash
shell$ jobber task.list retry
[2022-04-06T12:12:09] tasks changed to state Q: 4
shell$ jobber task.list print:queued
#!/bin/bash
# task 2 worker 2 queued
sleep 1; echo '--task-2--'; exit 1
# task 4 worker 4 queued
sleep 1; echo '--task-4--'; exit 1
# task 6 worker 6 queued
sleep 1; echo '--task-6--'; exit 1
# task 8 worker 8 queued
sleep 1; echo '--task-8--'; exit 1
shell$