How to cat /dev/ttyUSB0 to new file daily

Question

I have a script that simply does this:

cat /dev/ttyUSB0 > /home/pi/usb0_$(date +\%Y\%m\%d\%H\%M\%S).txt

It runs great, but I want to create a new file each day instead of one big file.

I thought about using crontab to do this, but I don't know how to get the first day's job to end before starting the next.

Answer 1

There's the timeout utility in GNU coreutils for exactly that, run:

timeout 86400 cat ... > ...

Answer 2

Another option would be to skip the needless complication of killing daily and instead pipe the output to e.g. rotatelog or cronolog that would then daily rotate the output to a new file.

... | ...rotatelogs -l /home/pi/usb0_%Y%m%d 86400