How can I minify JSON in a shell script?

Question

I've been looking for a way to uglify some JSON while in my bash console. This help using it afterward in another command (for example, to pass json inline to httpie)

Giving:

{
    "foo": "lorem",
    "bar": "ipsum"
}

I want to obtain:

{"foo":"lorem","bar":"ipsum"}

_{NOTE: this question is intentionnaly greatly inspired by it's pretty-print counterpart. However, googling for bash minify json didn't give me a proper result, hence this questions for the minify/uglify.}

Answer 1

You can use jq -c (compact) option.

jq -c . < input.json

Answer 2

TL;DR

no install

python -c 'import json, sys;json.dump(json.load(sys.stdin), sys.stdout)' < my.json

very fast (with jj)

jj -u < my.json

Perf benchmark

Here's the script, using hyperfine:

#!/usr/bin/env bash

tmp=$(mktemp json.XXX)
tmp_md=$(mktemp md.XXX)

trap "rm $tmp $tmp_md" EXIT

cat <<JSON > $tmp
{
    "foo": "lorem",
    "bar": "ipsum"
}
JSON
hyperfine \
    --export-markdown $tmp_md \
    --warmup 100 \
    "jj -u < $tmp" \
    "yq eval -j -I=0 < $tmp" \
    "xidel -s - -e '\$json' --printed-json-format=compact < $tmp" \
    "jq --compact-output < $tmp" \
    "python3 -c 'import json, sys;json.dump(json.load(sys.stdin), sys.stdout)' < $tmp" \
    "ruby -r json -e 'j JSON.parse \$stdin.read' < $tmp"

pbcopy < $tmp_md

The result on my mac — MacBook Air (M1, 2020), 8 GB:

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
jj -u < json.p72	1.3 ± 0.2	0.9	2.7	1.00
yq eval -j -I=0 < json.p72	4.4 ± 0.4	3.8	7.8	3.37 ± 0.65
xidel -s - -e '$json' --printed-json-format=compact < json.p72	5.5 ± 0.3	5.0	6.5	4.19 ± 0.77
python3 -c 'import json, sys;json.dump(json.load(sys.stdin), sys.stdout)' < json.p72	14.0 ± 0.4	13.4	15.0	10.71 ± 1.89
jq --compact-output < json.p72	14.4 ± 2.0	13.2	33.6	11.02 ± 2.45
ruby -r json -e 'j JSON.parse $stdin.read' < json.p72	47.3 ± 0.6	46.1	48.5	36.10 ± 6.32

Result for a large JSON file (14k lines):

http https://france-geojson.gregoiredavid.fr/repo/regions.geojson | jj -p > $tmp

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
jj -u < json.wFY	3.4 ± 0.7	2.7	12.2	1.00
jq --compact-output < json.wFY	35.1 ± 0.4	34.5	36.1	10.24 ± 2.23
python3 -c 'import json, sys;json.dump(json.load(sys.stdin), sys.stdout)' < json.wFY	47.4 ± 0.5	46.3	48.7	13.82 ± 3.01
xidel -s - -e '$json' --printed-json-format=compact < json.wFY	55.5 ± 1.2	54.7	63.5	16.17 ± 3.53
ruby -r json -e 'j JSON.parse $stdin.read' < json.wFY	94.9 ± 0.7	93.8	96.8	27.65 ± 6.02
yq eval -j -I=0 < json.wFY	3087.0 ± 26.6	3049.3	3126.8	899.63 ± 195.81

_{And here is the pretty print counterpart benchmark}

Answer 3

yq worked for me, via utilization of input file (containing the prettified JSON)
yq eval -j -I=0 uglify-test.txt
Docs link: https://mikefarah.gitbook.io/yq/usage/convert

Answer 4

With xidel:

xidel -s input.json -e '$json' --printed-json-format=compact
#or
xidel -s input.json -e 'serialize-json($json)'
{"foo": "lorem", "bar": "ipsum"}

Interesting "benchmark", Ulysse BN.
I couldn't test jj, but on my old cpu these are my results:

var='{
    "foo": "lorem",
    "bar": "ipsum"
}'

time (for i in {1..100}; do python -c 'import json, sys;json.dump(json.load(sys.stdin), sys.stdout)' <<< "$var" >& /dev/null; done)

real    0m10.813s
user    0m7.532s
sys     0m5.798s

time (for i in {1..100}; do jq --compact-output <<< "$var" >& /dev/null; done)

real    0m10.500s
user    0m1.835s
sys     0m0.769s

time (for i in {1..100}; do xidel -se '$json' --printed-json-format=compact <<< "$var" >& /dev/null; done)

real    0m2.250s
user    0m1.692s
sys     0m0.889s

Answer 5

jq-minify

Here is a bash script that will write back to the file minified

works with bash v3.2+ and jq v1.6+

#!/usr/bin/env bash
set -eu
path=
options=()
# change -c to -r to get pretty-print
set -- "$@" -c .
for arg; do
  if [ -f "$arg" ]; then
    if [ -n "$path" ]; then
      echo "Cannot specify multiple paths to jq-minify" >&2
      exit 1
    fi
    path="$arg"
  else
    options+=("$arg")
  fi
done
tmp=$(mktemp)
jq "${options[@]}" "$path" >"$tmp"
cat "$tmp" >"$path"