jq の入力・真偽・シェルとの受け渡し

$ printf '{"a":1}{"b":2}' | jq -c .; echo "rc=$?"
{"a":1}
{"b":2}
rc=0
$ printf '{"error":"boom"}{"branch":"x"}' | jq -r .branch; echo "rc=$?"
null
x
rc=0

$ v=$(printf '{"error":"boom"}{"branch":"x"}' | jq -r .branch); [[ $v == null ]] && echo 'null と判定' || echo "null でないと判定: [$v]"
null でないと判定: [null
x]

$ printf '{"a":1} garbage' > bad.json
$ jq -c . bad.json; echo "rc=$?"
jq: parse error: Invalid numeric literal at EOF at line 1, column 15
{"a":1}
rc=5
$ x=$(jq -c . bad.json); echo "rc=$? x=$x"
jq: parse error: Invalid numeric literal at EOF at line 1, column 15
rc=5 x={"a":1}

$ jq -s -c 'if length == 1 then .[0] else error("not a single value") end' bad.json; echo "rc=$?"
jq: parse error: Invalid numeric literal at EOF at line 1, column 15
rc=5
$ printf '{"a":1}{"b":2}' | jq -s -c 'if length == 1 then .[0] else error("not a single value") end'; echo "rc=$?"
jq: error (at <stdin>:0): not a single value
rc=5
$ printf '{"a":1}' | jq -s -c 'if length == 1 then .[0] else error("not a single value") end'; echo "rc=$?"
{"a":1}
rc=0

$ printf '{"branch":"null チェック"}' | jq -e -s 'length == 1 and (.[0] | type == "object") and (.[0].branch | type == "string" and length > 0)' >/dev/null; echo "rc=$?"
rc=0
$ printf '{"branch":null}' | jq -e -s 'length == 1 and (.[0] | type == "object") and (.[0].branch | type == "string" and length > 0)' >/dev/null; echo "rc=$?"
rc=1
$ printf '{"error":"boom"}{"branch":"x"}' | jq -e -s 'length == 1 and (.[0] | type == "object") and (.[0].branch | type == "string" and length > 0)' >/dev/null; echo "rc=$?"
rc=1

$ printf '{"a":1}\n{"a":2\n{"a":3}\n' > mid.jsonl
$ jq -c . mid.jsonl; echo "rc=$?"
jq: parse error: Expected separator between values at line 3, column 1
{"a":1}
rc=5
$ jq -c -s 'length' mid.jsonl; echo "rc=$?"
jq: parse error: Expected separator between values at line 3, column 1
rc=5
$ jq -Rc 'fromjson? | .a' mid.jsonl; echo "rc=$?"
1
3
rc=0

$ printf '{"a":1}\n{"a":2}\n{"a":3' > tail.jsonl
$ jq -c -s 'length' tail.jsonl; echo "rc=$?"
jq: parse error: Unfinished JSON term at EOF at line 3, column 6
rc=5
$ jq -Rc 'fromjson? | .a' tail.jsonl; echo "rc=$?"
1
2
rc=0

$ echo '[false,null,0,"",[],{}]' | jq -c '.[] | {v: ., truthy: (if . then true else false end)}'
{"v":false,"truthy":false}
{"v":null,"truthy":false}
{"v":0,"truthy":true}
{"v":"","truthy":true}
{"v":[],"truthy":true}
{"v":{},"truthy":true}

$ echo '[{"id":1},{"id":2,"waiting":false},{"id":3,"waiting":true}]' > w.json
$ jq -c '.[] | select(.waiting | not)' w.json
{"id":1}
{"id":2,"waiting":false}
$ jq -c '.[] | select(.waiting == false)' w.json
{"id":2,"waiting":false}
$ echo '[{"id":1,"blocked":[]},{"id":2,"blocked":["x"]},{"id":3}]' > b.json
$ jq -c '.[] | select(.blocked)' b.json
{"id":1,"blocked":[]}
{"id":2,"blocked":["x"]}
$ jq -c '.[] | select((.blocked | length) > 0)' b.json
{"id":2,"blocked":["x"]}

$ echo '[{"id":1},{"id":2,"rank":0},{"id":3,"rank":1}]' > r.json
$ jq -c '.[] | select(.rank)' r.json
{"id":2,"rank":0}
{"id":3,"rank":1}
$ jq -c '.[] | select(.rank > 0)' r.json
{"id":3,"rank":1}

$ echo '[{"id":1,"visible":false},{"id":2,"visible":null},{"id":3},{"id":4,"visible":true}]' > n.json
$ jq -c '.[] | {id, v: (.visible // true)}' n.json
{"id":1,"v":true}
{"id":2,"v":true}
{"id":3,"v":true}
{"id":4,"v":true}
$ jq -c '.[] | if (.visible // true) == false then empty else .id end' n.json
1
2
3
4
$ jq -c '.[] | if .visible == false then empty else .id end' n.json
2
3
4

$ echo '[{"id":1,"children":[{"id":2}]}]' > t.json
$ jq -c '.[] | recurse(.children[])' t.json; echo "rc=$?"
jq: error (at t.json:1): Cannot iterate over null (null)
{"id":1,"children":[{"id":2}]}
{"id":2}
rc=5
$ jq -c '.[] | recurse(.children[]?)' t.json; echo "rc=$?"
{"id":1,"children":[{"id":2}]}
{"id":2}
rc=0
$ jq -c '.[] | select(.id == 2)' t.json; echo "rc=$?"
rc=0
$ jq -c '.[] | recurse(.children[]?) | select(.id == 2)' t.json; echo "rc=$?"
{"id":2}
rc=0

$ echo '{"id":1,"children":[{"id":2,"visible":false,"children":[{"id":3}]},{"id":4}]}' > v.json
$ jq -c '[recurse(.children[]?) | .id]' v.json
[1,2,3,4]
$ jq -c '[recurse(.children[]?) | select(.visible != false) | .id]' v.json
[1,3,4]
$ jq -c '[recurse(.children[]?; .visible != false) | .id]' v.json
[1,4]

$ echo '{"id":1,"visible":false,"children":[{"id":2}]}' | jq -c '[recurse(.children[]?; .visible != false) | .id]'
[1,2]

$ jq -rn '["a\nb", "c\td"] | @tsv'
a\nb	c\td
$ jq -rn '{note: "a\nb"} | ["id1", @json] | @tsv' > t.tsv
$ cat t.tsv
id1	{"note":"a\\nb"}
$ cut -f2 t.tsv | jq -r .note
a\nb

$ jq -rn '{note: "a\nb"} | ["id1", (@json | @base64)] | @tsv' > b.tsv
$ cat b.tsv
id1	eyJub3RlIjoiYVxuYiJ9
$ cut -f2 b.tsv | base64 -d | jq -r .note
a
b

$ jq -rn '["a", "", "c"] | @tsv' | od -c | head -1
0000000   a  \t  \t   c  \n
$ jq -rn '["a", "", "c"] | @tsv' | { IFS=$'\t' read -r x y z; echo "x=[$x] y=[$y] z=[$z]"; }
x=[a] y=[c] z=[]
$ jq -rn '["", "b", "c"] | @tsv' | { IFS=$'\t' read -r x y z; echo "x=[$x] y=[$y] z=[$z]"; }
x=[b] y=[c] z=[]

$ jq -rn '["", "b", "c"] | @tsv' | awk -F'\t' '{print "x=[" $1 "] y=[" $2 "] z=[" $3 "]"}'
x=[] y=[b] z=[c]
$ jq -rn '["a", "", "c"] | join("\u001f")' | { IFS=$'\x1f' read -r x y z; echo "x=[$x] y=[$y] z=[$z]"; }
x=[a] y=[] z=[c]
$ jq -rn '["", "b", "c"] | join("\u001f")' | { IFS=$'\x1f' read -r x y z; echo "x=[$x] y=[$y] z=[$z]"; }
x=[] y=[b] z=[c]

$ printf 'x\ny\n' | jq -Rs .
"x\ny\n"
$ printf '*bold* line1\nback\\slash\n日本語\n' | jq -Rsc --arg color good 'rtrimstr("\n") as $m | [{$color, text: $m}]'
[{"color":"good","text":"*bold* line1\nback\\slash\n日本語"}]

$ printf 'x\n' | jq -Rs --arg color good '{color}'; echo "rc=$?"
jq: error (at <stdin>:1): Cannot index string with string ("color")
rc=5

$ getconf ARG_MAX
2097152
$ long=$(head -c 131071 /dev/zero | tr '\0' a); jq -n --arg x "$long" '$x | length'; echo "rc=$?"
131071
rc=0
$ long=$(head -c 131072 /dev/zero | tr '\0' a); jq -n --arg x "$long" '$x | length'; echo "rc=$?"
bash: line 1: /usr/bin/jq: Argument list too long
rc=126

$ long=$(head -c 131071 /dev/zero | tr '\0' a); args=(); for i in $(seq 10); do args+=("$long"); done; jq -n '$ARGS.positional | length' --args "${args[@]}"; echo "rc=$?"
10
rc=0
$ long=$(head -c 131071 /dev/zero | tr '\0' a); args=(); for i in $(seq 20); do args+=("$long"); done; jq -n '$ARGS.positional | length' --args "${args[@]}"; echo "rc=$?"
bash: line 1: /usr/bin/jq: Argument list too long
rc=126

$ long=$(head -c 3000000 /dev/zero | tr '\0' a); printf '%s' "$long" | jq -Rs 'length'; echo "rc=$?"
3000000
rc=0

$ wc -c spec.json
1105630 spec.json
$ time (jq -r '.paths | keys[]' spec.json | while read -r p; do jq -r --arg p "$p" '.paths[$p].get.summary | length' spec.json; done > /dev/null)

real	0m3.165s
user	0m2.399s
sys	0m0.770s
$ time (jq -c '.paths | to_entries[]' spec.json | while read -r l; do jq -r '.value.get.summary | length' <<<"$l"; done > /dev/null)

real	0m1.580s
user	0m0.777s
sys	0m0.822s
$ time (jq -r '.paths | to_entries[] | .value.get.summary | length' spec.json > /dev/null)

real	0m0.010s
user	0m0.008s
sys	0m0.002s