How to extract max value among values between 2 words with multiple occurrence from input string using shell script

Question

I want to extract the maximum temperature value from the output of a command, which I store in a shell variable as follows:

res="$(get temperature all)"

where the result looks like

 Device 0 avs data:
    Temperature: 33.5 C
    voltage1V0:  0.926 V
    voltage1V8:  1.782 V
    voltage3V3:  3.265 V

 Device 1 avs data:
    Temperature: 32.6 C
    voltage1V0:  0.923 V
    voltage1V8:  1.780 V
    voltage3V3:  3.265 V

 Device 2 avs data:
    Temperature: 33.1 C
    voltage1V0:  0.920 V
    voltage1V8:  1.785 V
    voltage3V3:  3.290 V

 Device 3 avs data:
    Temperature: 33.1 C
    voltage1V0:  0.921 V
    voltage1V8:  1.780 V
    voltage3V3:  3.265 V

I want to extract the numerical value enclosed between the strings Temperature: and C, and find the maximum value from all the device records. For the above case, the output should be

33.5

since the temperature values are 33.5, 32.6, 33.1, 33.1

In the above command, the output gives

• sometimes only Device 0 information,
• sometimes Device 0, Device 1 information
• sometimes Device 0, Device 1, Device 3, Device 4 information

so finding max temperature logic should be generic irrespective of devices count (though the max count is 4, min count is 1 for available devices).

So for example, if only a single device is present then the max temperature should be equal to device 0 temperature, otherwise we need to compare and print.

Edit 1 - I need to use sed or awk as grep -P option is not available.

echo 'Here is a string, and Here is another string.' | grep -oP '(?<=Here).*(?=string)'

grep: invalid option -- 'P'

Answer 1

Assuming every device can contain only one "Temperature" reading, and you are only interested in printing the maximum (and not the associated device number), you can try the following:

awk '$1=="Temperature:" {if ($2>max) max=$2} END{printf("Maximum: %.1f\n",max)}'

This will parse all lines where the first space-separated field ($1) is Temperature:, and inspect the second field ($2, which is the numerical temperature value). If that is larger than the maximum so far, it is stored in the variable max (which behaves as if it were initially 0).

At the end, this maximum found is printed.