Bash regex match on JSON structure

Question

I have a JSON structure like this which I've read into a bash variable as a string:

{
        "elem1": "val1",
        "THEELEM": "THEVAL",
        "elem3": "val3"
}

I want to use regex to match on "THEELEM": "THEVAL". It works if I try individual words, where the JSON is stored in result as a string:

[[ $result =~ THEVAL ]] && echo "yes"

But I want to match on the key-pair like this:

[[ $result =~ "THEELEM": "THEVAL" ]] && echo "yes"

That gives me syntax issues. I've tried escaping, single-quotes and triple quotes to no avail. Any help appreciated.

More generally, you should use the jq utility to parse JSON in bash. — Barmar
– Barmar, Commented Jun 11, 2019 at 21:39

Barmar · Accepted Answer · 2019-06-12 17:20:21Z

1

Quoting works for me.

[[ $result =~ '"THEELEM": "THEVAL"' ]] && echo "yes"

Note that quoting the pattern disables recognition of special regular expression characters, and just searches for the literal substring. This is not a problem here, since you don't have any wildcards or other non-literal pattern characters. But if you did, you'd have to put the pattern in a variable, as in @noah's answer.

edited Jun 12, 2019 at 17:20

answered Jun 11, 2019 at 21:39

Barmar

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2 Comments

Charles Duffy Over a year ago

...though it's an exact substring match rather than a regex match in this usage mode.

Barmar Over a year ago

@CharlesDuffy Good catch. The man page on my Mac doesn't mention that (although it's true in the implementation), but I found the explanation in the online bash manual.

noah · Accepted Answer · 2019-06-11 23:51:28Z

1

You can create a variable $expr to hold the string you want to match to and then use that for the regex.

expr='"THEELEM": "THEVAL"'
[[ $result =~ $expr ]] && echo "yes"

Inspired by this stack overflow post

edited Jun 11, 2019 at 23:51

answered Jun 11, 2019 at 21:30

noah

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1 Comment

Benjamin W. Over a year ago

You can't have blanks around = in an assignment.

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