echo "$SOME_JSON" | jq '.[]' --raw-output --compact-output | while read -r LINE ; do ... ; done
...lets you process stuff "record by record" pretty consistently. (and `( xxx ; yyy ; zzz ) | jq --slurp '.'` lets you do the reverse, "absorbing" multiple records into an array.
...lets you "load" json for merging, processing, formatting, etc. The leading "{}" is moderately necessary because `jq` technically _processes_ json, not generates it.
Finally, it's a huge cheat code for string formatting!!
$ echo "{}" | jq \
--arg FOO "hello \$world" \
--arg BAR "complicated \| chars" \
--arg ONE 1 \
--arg TWO 2 \
'"aaa \( $FOO ) and \( $BAR ) and \( ($ONE | tonumber) + ($TWO | tonumber) ) bbb"'
"aaa hello $world and complicated \\| chars and 3 bbb"
...optionally with `--raw-output` (un-json-quoted), and even supports some regex substitution in strings via `... | gsub(...)`.
Yes, yes... it's overly complicated compared to you and your fancy "programming languages", but sometimes with shell stuff, the ability to _CAPTURE_ arbitrary command output (eg: `--argjson LS_OUTPUT="$( ls -lart ... )"`), but then also use JSON/jq to _safely_ marshal/deaden the data into JSON is really helpful!
> The leading "{}" is moderately necessary because `jq` technically _processes_ json, not generates it.
The --null-input/-n option is the "out-of-the-box" way to achieve this, and avoids a pipe (usually not a big deal, but leaves stdin free and sometimes saves a fork).
This lets you rewrite your first "pattern":
jq -cnr --argjson SOME_JSON "$SOME_JSON" '$SOME_JSON[]' | while read ...
We also have a "useless use of cat": --slurpfile does that job better:
jq -n --slurpfile FOO test.json '{bar: $FOO[]}'
(assuming you are assured that test.json contains one json value; --argjson will immediately fail if this is not the case, but with --slurpjson you may need to check that $FOO is a 1-item array.)
And of course, for exactly the single-file single-object case, you can just write:
Don't forget `--argjson`
...lets you "load" json for merging, processing, formatting, etc. The leading "{}" is moderately necessary because `jq` technically _processes_ json, not generates it.Finally, it's a huge cheat code for string formatting!!
...optionally with `--raw-output` (un-json-quoted), and even supports some regex substitution in strings via `... | gsub(...)`.Yes, yes... it's overly complicated compared to you and your fancy "programming languages", but sometimes with shell stuff, the ability to _CAPTURE_ arbitrary command output (eg: `--argjson LS_OUTPUT="$( ls -lart ... )"`), but then also use JSON/jq to _safely_ marshal/deaden the data into JSON is really helpful!