Question

How to start a shell script in one minute later?

Suppose there are two bash files a.sh and b.sh
I want to execute b.sh one minute(or several seconds) after a.sh executed.
what should I code in a.sh ?

Answer 1

Simple. you want to use ‘at’ to schedule your job. and ‘date’ to calculate your moment in the future.

Example:

echo b.sh | at now + 1 minute

or:

echo b.sh | at -t `date -v+60S "+%Y%m%d%H%M%S"`

-v+60S adds 60 seconds to current time. You can control exactly how many seconds you want to add.

But usually, when people wants one program to launch a minute after the other, they are not 100% sure it will not take more or less than a minute. that’s it. b.sh could be launched before a.sh is finished. or a.sh could have finished 30 seconds earlier than “planned” and b.sh could have started faster.

I would recommend a different model. Where b.sh is launched first.
a.sh creates a temp file when it starts. execute is tasks and delete its temp file at the end.
b.sh watch for the temp file to be created, then deleted. and start its tasks.