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155 lines
2.8 KiB
Plaintext
155 lines
2.8 KiB
Plaintext
# jq
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# A lightweight and flexible command-line JSON processor.
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# Output a JSON file, in pretty-print format:
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jq
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# Output all elements from arrays
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# (or all key-value pairs from objects) in a JSON file:
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jq .[]
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# Read JSON objects from a file into an array, and output it
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# (inverse of jq .[]):
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jq --slurp
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# Output the first element in a JSON file:
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jq .[0]
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# Output the value of a given key of the first element in a JSON file:
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jq .[0].key_name
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# Output the value of a given key of each element in a JSON file:
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jq 'map(.key_name)'
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#
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# [ { foo: 1 }, { foo: 2 } ]
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# => [1, 2]
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# Extract as stream of values instead of a list
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jq '.[] | .foo'
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#
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# [ { "foo": 1 }, { "foo": 2 } ]
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# => 1, 2
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# Slicing
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jq '.[1:2]'
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#
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# [ { "foo": 1 }, { "foo": 2 } ]
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# => { "foo": 2 }
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# Dictionary subset shorthand
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jq 'map({ a, b })'
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#
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# [ { "a": 1, "b": 2, "c": 3 }, ...]
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# => [ { "a": 1, "b": 2 }, ...]
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# Converting arbitrary data to json
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jq -r '(map(keys) | add | unique | sort) as $cols \
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| .[] as $row | $cols | map($row[.]) | @csv'
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#
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# [ { "foo": 1, "bar": 2}, { "foo": 3, "baz": 4}]
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#
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# => 2,,1
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# ,4,3
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# Filter a list of objects
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jq 'map(select(.name == "foo"))'
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#
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# [ { "name": "foo" }, { "name": "bar" } ]
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# => [ { "name": "foo" } ]
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#
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# ## mapping and transforming ##
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#
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# Add + 1 to all items
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jq 'map(.+1)'
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# Delete 2 items
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jq 'del(.[1, 2])'
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# Concatenate arrays
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jq 'add'
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# Flatten an array
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jq 'flatten'
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#
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# [[1], [2]]
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# => [1, 2]
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# Create a range of numbers
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jq '[range(2;4)]'
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# Display the type of each item
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jq 'map(type)'
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# Sort an array of basic type
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jq 'sort'
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#
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# [3, 2, 1]
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# => [1, 2, 3]
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# Sort an array of objects
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jq 'sort_by(.foo)'
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# Sort lines of a file
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jq --slurp '. | sort | .[]'
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# Group by a key - opposite to flatten
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jq 'group_by(.foo)'
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# Minimun value of an array
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jq 'min'
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# See also min, max, min_by(path_exp), max_by(path_exp)
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# Remove duplicates
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jq 'unique'
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# or
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jq 'unique_by(.foo)'
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# or
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jq 'unique_by(length)'
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#
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# [1, 1, 2, 1]
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# => [1, 2]
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# Reverse an array
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jq 'reverse'
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#
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# ## jq in shell scripts ##
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#
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# URL Encode something
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date | jq -sRr @uri
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# Thu%2021%20May%202020%2012%3A40%3A40%20PM%20CEST%0A
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# To create proper JSON from a shell script and properly escape variables:
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jq -n --arg foobaz "$FOOBAZ" '{"foobaz":$foobaz}'
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# To fill environment variables from JSON object keys
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# (e.g. $FOO from jq query ".foo")
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export $(jq -r '@sh "FOO=\(.foo) BAZ=\(.baz)"')
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#
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# ## Input/output formats ##
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#
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# Parsing json
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jq 'with_entries(.value |= fromjson)' --sort-keys
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#
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# { "b": "{}", "a": "{}" }
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# => { "a": {}, "b": {} }
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# Serializing json
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#
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jq 'with_entries(.value |= tojson)' --sort-keys
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#
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# { "a": {}, "b": {} }
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# => { "a": "{}", "b": "{}" }
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# Converting to csv
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jq '.[] | [.foo, .bar] | @csv' -r
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#
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# [{ "foo": 1, "bar": 2, "baz":3 }]
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# => 1,2
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