How do I sum all numbers from output of jq

Another option (and one that works even if not all your durations are integers) is to make your jq code do the work:

sample_data='{"duration": 1211789}
{"duration": 1211789}
{"duration": 373585}
{"duration": 495379}
{"duration": 1211789}'

jq -n '[inputs | .duration] | reduce .[] as $num (0; .+$num)' <<<"$sample_data"

...properly emits as output:

4504331

Replace the <<<"$sample_data" with a pipeline on stdin as desired.

the simplest solution is the add filter:

jq '[.duration] | add'

the [ brackets ] are needed around the value to sum because add sums the values of an array, not a stream. (for stream summation, you would need a more sophisticated solution, e.g. using reduce, as detailed in other answers.)

---

depending on the exact format of the input, you may need some preprocessing to get this right.

e.g. for the sample input in Charles Duffy’s answer either

• use inputs (note that -n is needed to avoid jq swallowing the first line of input):

  jq -n '[inputs.duration] | add' <<< "$sample_data"
  

• or slurp (-s) and iterate (.[]) / map:

  jq -s '[.[].duration] | add' <<< "$sample_data"
  jq -s 'map(.duration) | add' <<< "$sample_data"