Wednesday, August 27, 2014

Simple asynchronous task spawn from shell

Yesterday was a hard day at work! I was meddling with some shell (bash) script, where I had to make a CLI work; a CLI command which would restart self (the whole set of services, including the ones who spawned the CLI).

That was somehow not working! before the script could restart the services, it would get terminated! I did a lot of reading, and learnt lot many bash tricks in a day that I haven't learnt in a long time! :)

Now, for this issue, what I needed was a way to tell someone "Please restart me" because "I'm not able to restart myself!" - ah! asynchronous task/job.

I already had a daemon to execute a task, but since it was also part of the processes that get killed on restart - I could not use it. I have a simple shell script, and I needed no additional complexity, what could I do ? ... a little more digging on stackexchange led me to a simple solution.

Schedule a job to be executed at a later time (or immediately) using at!

So, my solution boiled down to a very simple change, instead of restart, I had to say

restart | at now 


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