Reading Raw Text into jq

November 3, 2021

How do you read non-JSON inputs with jq?

This isn’t obvious if you don’t already know how to do it…

The manual says:


Don't parse the input as JSON. Instead, each line of text is passed to the
filter as a string. If combined with --slurp, then the entire input is passed
to the filter as a single long string.

Clear yet?

An Example

$ cat fruits.txt

$ cat fruits.txt | jq --raw-input .
"cherry    "

The lines in fruits.txt are “naked” strings; not JSON strings (missing double quotes). What --raw-input does is wrap your lines in double quotes: notice the dangling spaces after cherry.

If you try to load fruits.txt without --raw-input, you get:

$ cat fruits.txt | jq .
parse error: Invalid numeric literal at line 2, column 0

Once “bootstrapped” into jq, you can treat it as any JSON input:

$ cat fruits.txt | jq --raw-input '{(.): (. | length)}' -c
{"cherry    ":10}


Technically, fruits.txt contains 6 lines: it becomes 6 JSON items, treated separately.

If you’ve done enough jq, your solution is to --slurp it, to get an array of strings:

$ cat fruits.txt | jq --raw-input --slurp .
"apple\nbanana\ncherry    \nkiwi\norange\npeach\n"

Oh no … 😬

As per the --raw-input documentation (helpfully at the top of this post), --slurp works surprisingly for this case… The whole input, all the lines, is considered as one giant string.

What’s the workaround? As far as I could tell, you are going to need two jq commands to make this work:

$ cat fruits.txt | jq --raw-input . | jq --slurp .
  "cherry    ",

$ cat fruits.txt | jq --raw-input . | jq --slurp . -c
["apple","banana","cherry    ","kiwi","orange","peach"]


jq is wonderful once you have JSON … but a lot of command-line tools don’t produce JSON natively.

Using this technique, you can uplift raw text into JSON and modify it into the shape you need. All the while, you are guaranteed to keep and generate valid JSON outputs.

The alternatives of text manipulation with sed/awk/perl/etc are (at best!) too error-prone.

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