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"}

_{See the pretty-print counterpart.}

suggestion: add some white-space to the sample strings here. — orion elenzil
– orion elenzil, Commented Aug 30, 2023 at 15:56
I'm not sure about what you are meaning @orionelenzil, but i you mean strings with spaces inside (" lorem. "), I'm not expecting those to be compacted afterward. This question is just an example btw, you'll see that the answer also use an external, way larger json — Ulysse BN
– Ulysse BN, Commented Aug 30, 2023 at 19:56
right, it's a minor thing but with your existing example naively removing whitespace would work fine, but if there were whitespace in the values or keys then such a simple approach would not work, thus motivating the use of something fancier like the suggestions in the answers. — orion elenzil
– orion elenzil, Commented Aug 30, 2023 at 20:40
Sorry, I don't seem to get what you want... I'd rather keep it simple anyway, this is not a use case, just an example! — Ulysse BN
– Ulysse BN, Commented Aug 30, 2023 at 20:53

guizo · Accepted Answer · 2021-01-31 21:40:29Z

93

You can use jq -c (compact) option.

jq -c . < input.json

answered Jan 31, 2021 at 21:40

guizo

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4 Comments

Cornelius Roemer Over a year ago

Doesn't work if you have a deeply nested JSON file. See: stackoverflow.com/questions/75524357/…

Cornelius Roemer Over a year ago

In fact, the recursion limit of jq seems to be 512, see stackoverflow.com/a/75524782/7483211 and based on benchmarks jj is much faster!

gpinigin Over a year ago

cat input.json | jq -c > output.json is less awkward and more handy for huge files

bodgit Over a year ago

All you've done there is add an unnecessary cat

Ulysse BN · Accepted Answer · 2022-10-23 15:50:27Z

39

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}

edited Oct 23, 2022 at 15:50

answered Apr 9, 2020 at 15:46

Ulysse BN

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10 Comments

GChuf Over a year ago

How about uglify-js?

Ulysse BN Over a year ago

If you are talking about this: lisperator.net/uglifyjs, it is a javascript uglifier, not JSON. And node is less often available than python on computers. Hence I'm not sure it is a good candidate :/

Grant Foster Over a year ago

Example for the python line: python -c 'import json, sys;json.dump(json.load(sys.stdin), sys.stdout)' < myfile.json

Reino Over a year ago

@UlysseBN Could you include/update results for xidel's latest development build? Lots of improvements. Maybe you can also include xidel in your pretty print post?

orion elenzil Over a year ago

the 'no install' python command-line here produces not-fully-compacted JSON for me. it has spaces after : and ,'s. jq -c omits those spaces.

|

straville · Accepted Answer · 2021-08-20 09:30:42Z

1

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

answered Aug 20, 2021 at 9:30

straville

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1 Comment

Ulysse BN Over a year ago

I've added it to the benchmark! It seems surprisingly faster than jq !

Reino · Accepted Answer · 2025-03-31 00:35:54Z

0

With the JSON-parser and command line tool xidel:

$ xidel -s "input.json" -e '$json' --output-json-indent=compact
{"foo": "lorem", "bar": "ipsum"}

$ xidel -s "input.json" -e 'serialize($json,{"method":"json"})'
{"foo":"lorem","bar":"ipsum"}

Interesting "benchmark", @Ulysse BN. These are my results on an AMD Ryzen 3 3200U mobile cpu:

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

$ jq --version
jq-1.7
$ time (for i in {1..1000}; do jq --compact-output <<< "$var" >& /dev/null; done)

real    0m3.640s
user    0m0.862s
sys     0m0.686s

$ xidel --version
xidel 0.9.9 2025-02-22-git-3e7e88a62307
[...]
$ time (for i in {1..1000}; do xidel -se '$json' --output-json-indent=compact <<< "$var" >& /dev/null; done)

real    0m3.545s
user    0m0.958s
sys     0m0.709s

$ jj --version
jj - JSON Stream Editor 1.9.2
$ time (for i in {1..1000}; do jj -u <<< "$var" >& /dev/null; done)

real    0m2.453s
user    0m1.903s
sys     0m0.721s

edited Mar 31 at 0:35

answered Sep 7, 2020 at 10:16

Reino

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1 Comment

Ulysse BN Over a year ago

Very interesting solution! I've added it to my benchmark to have an answer easier to read :)

Sam Bacha · Accepted Answer · 2022-03-21 21:01:00Z

-2

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"

answered Mar 21, 2022 at 21:01

Sam Bacha

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2 Comments

Ulysse BN Over a year ago

I'm not sure I see this scripts point, why not jq -c file > file1 ?

Sam Bacha Jan 25 at 17:23

It creates a temporary file to safely transform the JSON before overwriting the original file with the processed version. As noted in the comments above, the command will error on deeply nested JSON objects. Also it prevents errors, like in your example: jq -c file > file1 is invalid, the correct command is jq -c . file > file1

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