Pretty simple script, but I am stuck.
It connects to a battery balancer, spits out the info into a json formatted file. I then have a pipe the output into jq to obtain the info I need. It works in the bash shell, but not in the script:
Here is the script:
echo "Checking battery voltages"
jkbms -p 3C:A5:19:7B:28:09 -o json > /home/bms/batt.log
echo cat /home/bms/batt.log | jq -r '.highest_cell_voltage'
echo "done"
The cat line shows this in the script output:
Checking battery voltages
parse error: Invalid numeric literal at line 1, column 4
done
From the shell it works as expected:
cat /home/bms/batt.log | jq -r '.highest_cell_voltage'
4.152044773101807
I have tried enclosing the whole cat command in quotes etc, but I am at a loss.
This, however, works:
echo "Checking battery voltages"
jkbms -p 3C:A5:19:7B:28:09 -o json > /home/bms/batt.log
batt=$(cat /home/bms/batt.log)
echo $batt | jq -r '.highest_cell_voltage'
#echo /usr/bin/cat /home/bms/batt.log
echo "done"
jkbms -p 3C:A5:19:7B:28:09 -o json > /home/bms/batt.log echo cat /home/bms/batt.log | jq -r '.highest_cell_voltage'
The echo here is wrong. By the way, you can simplify the above to:
jkbms -p 3C:A5:19:7B:28:09 -o json|tee /home/bms/batt.log|jq -r '.highest_cell_voltage'
If I need to print the output of the comand on the screen, how do i do it without using echo?
If you want the saved output in /home/bms/batt.log, you can cat /home/bms/batt.log anytime.
If you want to print the output of the comand on the screen only at the time of execution, you can tee /dev/tty instead of tee /home/bms/batt.log.
If at the time of execution you want the output on screen as well as in the log file, you can tee /home/bms/batt.log /dev/tty at once.