Using sed to extract number from json

Question

I'm struggling to use a single sed command to extract a number from some json on Linux. Given the following block:

{
    "key1": 100,
    "key2": 200,
}

I'd like the output to be 100 in the above case, but I need to capture it regardless of its length.

So far I've got this:

sed -n '/key1/ s/.*\: //p'
100,

I feel like I should be able to rid myself of the comma without piping out to 'tr' or whatever but I can't seem to manage it.

Answer 1

$ sed -e '/key1/!d' -e 's/.*\: //' -e 's/,//' testfile 
100

Answer 2

Just search for numbers:

$ sed -n '/key1/ s/.*\: \([0-9][0-9]*\).*/\1/p' file
100

or

$ sed -En '/key1/ s/.*\:\s+([0-9]+).*/\1/p' file
100

Personally, I would use grep instead though:

$ grep -oP 'key1":\s*\K\d+' file
100