Feature request: --tag-json

[Charles Howes]

Hi Ole;

Feature request: --tag-json

I'm dumping the state of my AWS resources using the CLI and getting JSON 
output, which I wrangle into a single JSON file per resource type, but 
it's an awful solution.

For example, given a list of profiles and regions, I might do this:

-------8<------cut here------8<---------
parallel --results "results/{1}/{2}" \
   aws --profile {1} elb describe-load-balancers --region {2} \
  :::: profiles.txt :::: regions.txt > /dev/null

export JQMERGE='( 
input_filename|sub("/stdout$";"")|sub("^[^/]*/";"")|gsub("/";" ") ) as 
$name | {"Name":$name,"Output":.}'

find results -name stdout -size +0 \
            | parallel jq -r '"$JQMERGE"' \
            | jq -s .  > describe-load-balancers.json
------->8------cut here------>8---------

This has evolved; initially, I tried doing tricks with --tag-string to 
generate json-style wrappers around the output, but it was a flimsy 
hack.

Could you add a feature that would emit one json object per job to 
stdout and result files, of the form:
  
{"Input":["arg1","arg2"],"Output":"..blah...blah...","Stderr":"...err...err..."}

I really can't think of a more robust way to do this, as any solution 
would have to deduce/reconstruct the information that Parallel already 
has.  Here's a working example of what I mean:

-------8<------cut here------8<---------
parallel '
  echo {1} {2} > stdout.{#} 2> stderr.{#} ;
  jq -R -s . stdout.{#} > stdout.{#}.json;
  jq -R -s . stderr.{#} > stderr.{#}.json;
  jq -c -n --arg in1 "{1}" --arg in2 "{2}" \
           --slurpfile stdout stdout.{#}.json \
           --slurpfile stderr stderr.{#}.json \
           
'"'"'{Input:[$in1,$in2],Stdout:$stdout[0],Stderr:$stderr[0]}'"'"'
           ' ::: red green ::: cat

{"Input":["red","cat"],"Stdout":"red cat\n","Stderr":""}
{"Input":["green","cat"],"Stdout":"green cat\n","Stderr":""}
------->8------cut here------>8---------

I'd really like it if that could be replaced by this:
-------8<------cut here------8<---------
parallell --tag-json echo {1} {2} ::: red green ::: cat > output.json
------->8------cut here------>8---------

Thanks!

--
Penelope Fudd (parallel@ch.pkts.ca)