John Siu Blog

JQ - Json Parser

☰ Table of Content

Cheat sheet for simple usage.

simple.json

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{
  "id":"01234567",
  "active":true,
  "name":{
    "first":"John",
    "last":"Siu"
  },
  "address": [
    "address line 1",
    "address line 2",
    "address line 3"
  ]
}

Command

Command	Usage
`jq '.' simple.json`	Print pretty
`jq '.id' simple.json`	Print value of `id`
`jq -r '.id' simple.json`	Print value of `id`, without quote
`jq '.id, .active' simple.json`	Print value of `id` and `active`
`jq '.name.last' simple.json`	Print value of `last` in `name`
`jq '.address[0]' simple.json`	Print first item of array `address`

Wildcard Select

jq don’t have wildcard select as of v1.6. So following does not work:

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journalctl -o json |jq -r '.| select(.SYSLOG_IDENTIFIER=="postfix*") | .SYSLOG_IDENTIFIER'

Workaround with select(|contains()) or select(|startswith()).

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journalctl -o json |jq -r '.| select(.SYSLOG_IDENTIFIER | contains("postfix")) | .SYSLOG_IDENTIFIER'
journalctl -o json |jq -r '.| select(.SYSLOG_IDENTIFIER | startswith("postfix")) | .SYSLOG_IDENTIFIER'

John Siu

Update: 2022-05-12

Tag

[cheatsheet]

[command-line]

[jq]

JQ - Json Parser

simple.json

Command

Wildcard Select

John Siu

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