Jq: Difference between revisions
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Selections within <code>()</code> are evaluated as expressions | Selections within <code>()</code> are evaluated as expressions | ||
</blockquote><!-- Expressions --> | </blockquote><!-- Expressions --> | ||
== Conditionals == | |||
<blockquote> | |||
Combined with <code>jq -e</code>, you can return true/false and map to an exitcode. | |||
<syntaxhighlight lang="bash"> | |||
echo '{"a": "foo"}' \ | |||
| jq -e '.a == "foo"' \ | |||
&& echo "success" | |||
</syntaxhighlight> | |||
</blockquote><!-- Conditionals --> | |||
== Operators == | == Operators == |
Revision as of 21:37, 29 January 2023
parse json on the commandline.
TODO:
the official docs are very good, but syntax could be documented consistently with other languages. (ex: datatypes etc)
Documentation
official docs https://stedolan.github.io/jq/manual/ basic filters docs https://stedolan.github.io/jq/manual/#Basicfilters homepage https://stedolan.github.io/jq/
Usage
Parameters
jq ${params..} ${query} [${file}] jq \ -r `# 'raw' remove quotes from retrieved strings` \ -e `# if result is 'true' exitcode is 0, if 'false' exitcode is 1`Basics
# print w/ syntaxhighlighting echo '{"one": 1, "two": {"a": "A"}}' | jq # get key ["one"] echo '{"one": 1, "two": {"a": "A"}}' | jq '.one' # 1 # get nested-key ["two"]["a"] echo '{"one": 1, "two": {"a": "A"}}' | jq '.two.a' # "A" # get list item at index 1 echo '["a", "b", "c"]' | jq '.[1]' # "b" echo '{"list": [{"a": 1}, {"a": 2}]}' | jq '.list[].a' # get 'a' key form every dict in listFilters
jq '.' # obj jq '.one' # obj["one"] jq '.one?' # obj["one"] (but no error if not exist) jq '.one.two' # obj["one"]["two"] jq '.[1]' # obj[1] jq '.[5:10]' # list-items 5-10 jq '.[] | select(.name == "foo") # all dicts in list where name=="foo" jq '.[] | select(.id == (242, 1, 123)) # all dicts where id in (242, 1, 123) jq '.[].name | select(startswith("foo"))' # all name keys from dicts that start with "foo" jq '.[] | with_entries(select(.key | in({"id": 1, "name": 1})))' # return subset of keys from dict (only: id, name)Expressions
Selections within
()
are evaluated as expressionsConditionals
Combined with
jq -e
, you can return true/false and map to an exitcode.echo '{"a": "foo"}' \ | jq -e '.a == "foo"' \ && echo "success"Operators
Used in expressions
+ - * / %Transform
You can compose new objects from the input object.
jq '{"fullname": (.firstname + .lastname)}'Comments
Neither json nor
jq
support comments.
It's hacky, but you could pre-process the object to strip them, however.echo '{ // syntax-highlight as javascript "local_path": "/home/you", // your home dir // a network path "netwk_path": "//10.1.0.5/music" }' \ | sed 's?//[^"]*$??' | jq '.one'