Convert TSV to JSON command line

So you've got some tsv data:

$: head foo.tsv
148 0.05 49.0530378784848
380 0.8 85.0345986160553
496 0.05 33.665653373865
612 0.15 58.1366745330187
728 0.1 60.8615655373785
844 0.3 69.4102235910563
960 0.2 74.4530218791248
1076 0.2 76.6129354825807
1192 2.25 99.0050397984081
1888 0.5 53.7328506859725

and you've got some field names (field_1,field_2,field_3). Try this:

$: export FIELDS=field_1,field_2,field_3
$: cat foo.tsv| ruby -rjson -ne 'puts ENV["FIELDS"].split(",").zip($_.strip.split("\t")).inject({}){|h,x| h[x[0]]=x[1];h}.to_json'

will give you something that looks like:

{"field_1":"148","field_2":"0.05","field_3":"49.0530378784848"}
{"field_1":"380","field_2":"0.8","field_3":"85.0345986160553"}
{"field_1":"496","field_2":"0.05","field_3":"33.665653373865"}
{"field_1":"612","field_2":"0.15","field_3":"58.1366745330187"}
{"field_1":"728","field_2":"0.1","field_3":"60.8615655373785"}
{"field_1":"844","field_2":"0.3","field_3":"69.4102235910563"}
{"field_1":"960","field_2":"0.2","field_3":"74.4530218791248"}
{"field_1":"1076","field_2":"0.2","field_3":"76.6129354825807"}
{"field_1":"1192","field_2":"2.25","field_3":"99.0050397984081"}
{"field_1":"1888","field_2":"0.5","field_3":"53.7328506859725"}

Hurray.