How to sync crontab with fcrontab, i.e. timer-based job and time-based job

Jay

1/6/23, 7:59 AM

Having 2 schedules set:

Cron running every 8am 0 8 * * * myCronJob.sh
Fcron running every 61 minutes: @1h1 myFcronJob.sh

They will eventually bump into each other and it will not work because in this scenario only one job can run at a time. To avoid this issue we might use a lock to allow only one job at a time, such as this code here

0 8 * * * user/bin/flock /usr/tmp/lfile.lockfile -c 'myCronJob.sh'

@ 1h1 user/bin/flock /usr/tmp/lfile.lockfile -c 'myFcronJob.sh'

This rises another issue, if fcron is configured to run every 61 minutes and when it starts and will wait for the other job to finish, the timer will be misaligned because the next time it runs, will be

(61 minutes - the time it had a lock on) It is required that the myFcronJob.sh runs after 60 minutes

Example

Cron job starts at 8am and runs for 5 minutes
Fcron is about to start at 8:01am too but it had noticed the lock is in place
Fcron waits for Cron job to finish
Fcron finally runs at 8:05am
Fcron will run 61 minutes from 8:01am which will result in next iteration to start at 9:02am instead of expected 9:06am

I was reading man page for fcrontab with hope there is some useful flag but couldn't understand much. Help appreciated

0 + 0

scripts

cron

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: How to sync crontab with fcrontab, i.e. timer-based job and time-based job

TH: วิธีซิงค์ crontab กับ fcrontab เช่น งานตามเวลาและงานตามเวลา

RO: Cum să sincronizați crontab cu fcrontab, adică job bazat pe temporizator și job bazat pe timp

RU: Как синхронизировать crontab с fcrontab, то есть задание на основе таймера и задание на основе времени

VI: Cách đồng bộ hóa crontab với fcrontab, tức là công việc dựa trên bộ đếm thời gian và công việc dựa trên thời gian

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