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jq 用法

jq 用法

作者: Rui哥 | 来源:发表于2022-03-15 22:18 被阅读0次

    jq 用法

    GitHub has a JSON API, so let's play with that. This URL gets us the last 5 commits from the jq repo.

    ## 方式0
curl 'https://api.github.com/repos/stedolan/jq/commits?per_page=5'

## 方式1 
curl 'https://api.github.com/repos/stedolan/jq/commits?per_page=5' | jq '.'

## 方式2
curl 'https://api.github.com/repos/stedolan/jq/commits?per_page=5' | jq '.[0]'

## 方式3
curl 'https://api.github.com/repos/stedolan/jq/commits?per_page=5' | jq '.[0] | {message: .commit.message, name: .commit.committer.name}'

## 方式4
curl 'https://api.github.com/repos/stedolan/jq/commits?per_page=5' | jq '.[] | {message: .commit.message, name: .commit.committer.name}'

## 方式5 
curl 'https://api.github.com/repos/stedolan/jq/commits?per_page=5' | jq '[.[] | {message: .commit.message, name: .commit.committer.name}]'

## 方式6
curl 'https://api.github.com/repos/stedolan/jq/commits?per_page=5' | jq '[.[] | {message: .commit.message, name: .commit.committer.name, parents: [.parents[].html_url]}]'

    1、网络请求原始数据

    # 操作 
curl 'https://api.github.com/repos/stedolan/jq/commits?per_page=5' 

# 响应
[
  {
    "sha": "a9f97e9e61a910a374a5d768244e8ad63f407d3e",
    "node_id": "C_kwDOAE3WVdoAKGE5Zjk3ZTllNjFhOTEwYTM3NGE1ZDc2ODI0NGU4YWQ2M2Y0MDdkM2U",
    "commit": {
      "author": {
        "name": "Nicolas Williams",
        "email": "nico@cryptonector.com",
        "date": "2021-10-21T05:17:39Z"
      },
      "committer": {
        "name": "Nicolas Williams",
        "email": "nico@cryptonector.com",
        "date": "2021-10-24T21:23:26Z"
      },
      "message": "Fix accidentally quadratic behavior in _modify\n\nWe need to be careful to not grab an extra reference when mutating data\nstructures because that means we make extra copies.  Doing that every\ntime in `_modify` is really painful, as that function implements `|=`\nand all modify-assign operators.\n\n`jv_setpath()` also grabs additional references, so this is not the only\nfix needed for the modify-assign operators to not be accidentally\nquadratic.\n\nWe have to use `LOADVN` in order to make this fix possible, so we should\nreally byte-code `_modify` rather than jq-code it.  However, as a\nstop-gap to make this fix easier, I'm adding syntax for referring to a\n`$binding` such that you get `LOADVN` instead of `LOADV`.\n\nThis syntax is not meant to be used outside jq's internals!  Therefore\nit is not documented.  I promise to break it later, so don't use it!\n\nTBD, but later:\n\n - Optimize `_modify` for the case where `update` outputs more than one\n   value.\n\n   This is trivial: add a `setpath($p; null)` in the middle of `_modify`\n   before calling `update`.  But unfortunately the VM retains a\n   reference to `value_at_path` for path expression checking, and fixing\n   that will require more work.",
      "tree": {
        "sha": "7883361d86bd97b1bcd2299fa5886182b27cee54",
        "url": "https://api.github.com/repos/stedolan/jq/git/trees/7883361d86bd97b1bcd2299fa5886182b27cee54"
      },
      "url": "https://api.github.com/repos/stedolan/jq/git/commits/a9f97e9e61a910a374a5d768244e8ad63f407d3e",
      "comment_count": 0,
      "verification": {
        "verified": false,
        "reason": "unsigned",
        "signature": null,
        "payload": null
      }
    },
    "url": "https://api.github.com/repos/stedolan/jq/commits/a9f97e9e61a910a374a5d768244e8ad63f407d3e",
    "html_url": "https://github.com/stedolan/jq/commit/a9f97e9e61a910a374a5d768244e8ad63f407d3e",
    "comments_url": "https://api.github.com/repos/stedolan/jq/commits/a9f97e9e61a910a374a5d768244e8ad63f407d3e/comments",
    "author": {
      "login": "nicowilliams",
      "id": 604851,
      "node_id": "MDQ6VXNlcjYwNDg1MQ==",
      "avatar_url": "https://avatars.githubusercontent.com/u/604851?v=4",
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      "gists_url": "https://api.github.com/users/nicowilliams/gists{/gist_id}",
      "starred_url": "https://api.github.com/users/nicowilliams/starred{/owner}{/repo}",
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      "events_url": "https://api.github.com/users/nicowilliams/events{/privacy}",
      "received_events_url": "https://api.github.com/users/nicowilliams/received_events",
      "type": "User",
      "site_admin": false
    },
    "committer": {
      "login": "nicowilliams",
      "id": 604851,
      "node_id": "MDQ6VXNlcjYwNDg1MQ==",
      "avatar_url": "https://avatars.githubusercontent.com/u/604851?v=4",
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      "url": "https://api.github.com/users/nicowilliams",
      "html_url": "https://github.com/nicowilliams",
      "followers_url": "https://api.github.com/users/nicowilliams/followers",
      "following_url": "https://api.github.com/users/nicowilliams/following{/other_user}",
      "gists_url": "https://api.github.com/users/nicowilliams/gists{/gist_id}",
      "starred_url": "https://api.github.com/users/nicowilliams/starred{/owner}{/repo}",
      "subscriptions_url": "https://api.github.com/users/nicowilliams/subscriptions",
      "organizations_url": "https://api.github.com/users/nicowilliams/orgs",
      "repos_url": "https://api.github.com/users/nicowilliams/repos",
      "events_url": "https://api.github.com/users/nicowilliams/events{/privacy}",
      "received_events_url": "https://api.github.com/users/nicowilliams/received_events",
      "type": "User",
      "site_admin": false
    },
    "parents": [
      {
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        "url": "https://api.github.com/repos/stedolan/jq/commits/0c3455d3290fa03da8c01c135dd7126a80ed28a8",
        "html_url": "https://github.com/stedolan/jq/commit/0c3455d3290fa03da8c01c135dd7126a80ed28a8"
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  },
  {
    "sha": "0c3455d3290fa03da8c01c135dd7126a80ed28a8",
    "node_id": "C_kwDOAE3WVdoAKDBjMzQ1NWQzMjkwZmEwM2RhOGMwMWMxMzVkZDcxMjZhODBlZDI4YTg",
    "commit": {
      "author": {
        "name": "Nicolas Williams",
        "email": "nico@cryptonector.com",
        "date": "2021-10-21T05:15:12Z"
      },
      "committer": {
        "name": "Nicolas Williams",
        "email": "nico@cryptonector.com",
        "date": "2021-10-24T21:23:26Z"
      },
      "message": "Fix accidentally quadratic behavior in setpath\n\nWe need to be careful to not grab an extra reference when mutating\ndata structures because that means we make extra copies.  Doing that\nevery time in `jv_setpath()` is really painful, as that function is used\nin `_modify/2`, which is used in `|=` and all modify-assign operators.\n\n`_modify` also grabs additional references, so this is not the only fix\nneeded for the modify-assign operators to not be accidentally quadratic.",
      "tree": {
        "sha": "2afb78228b16aaf0d28d5118edb8daab3b79234b",
        "url": "https://api.github.com/repos/stedolan/jq/git/trees/2afb78228b16aaf0d28d5118edb8daab3b79234b"
      },
      "url": "https://api.github.com/repos/stedolan/jq/git/commits/0c3455d3290fa03da8c01c135dd7126a80ed28a8",
      "comment_count": 0,
      "verification": {
        "verified": false,
        "reason": "unsigned",
        "signature": null,
        "payload": null
      }
    },
    "url": "https://api.github.com/repos/stedolan/jq/commits/0c3455d3290fa03da8c01c135dd7126a80ed28a8",
    "html_url": "https://github.com/stedolan/jq/commit/0c3455d3290fa03da8c01c135dd7126a80ed28a8",
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      "html_url": "https://github.com/nicowilliams",
      "followers_url": "https://api.github.com/users/nicowilliams/followers",
      "following_url": "https://api.github.com/users/nicowilliams/following{/other_user}",
      "gists_url": "https://api.github.com/users/nicowilliams/gists{/gist_id}",
      "starred_url": "https://api.github.com/users/nicowilliams/starred{/owner}{/repo}",
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      "type": "User",
      "site_admin": false
    },
    "committer": {
      "login": "nicowilliams",
      "id": 604851,
      "node_id": "MDQ6VXNlcjYwNDg1MQ==",
      "avatar_url": "https://avatars.githubusercontent.com/u/604851?v=4",
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      "url": "https://api.github.com/users/nicowilliams",
      "html_url": "https://github.com/nicowilliams",
      "followers_url": "https://api.github.com/users/nicowilliams/followers",
      "following_url": "https://api.github.com/users/nicowilliams/following{/other_user}",
      "gists_url": "https://api.github.com/users/nicowilliams/gists{/gist_id}",
      "starred_url": "https://api.github.com/users/nicowilliams/starred{/owner}{/repo}",
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      "site_admin": false
    },
    "parents": [
      {
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        "url": "https://api.github.com/repos/stedolan/jq/commits/1a1804afcb88cdc3f1f0e74e83385146b55ae205",
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  {
    "sha": "1a1804afcb88cdc3f1f0e74e83385146b55ae205",
    "node_id": "C_kwDOAE3WVdoAKDFhMTgwNGFmY2I4OGNkYzNmMWYwZTc0ZTgzMzg1MTQ2YjU1YWUyMDU",
    "commit": {
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        "email": "nico@cryptonector.com",
        "date": "2021-10-24T20:26:08Z"
      },
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        "name": "Nicolas Williams",
        "email": "nico@cryptonector.com",
        "date": "2021-10-24T21:23:26Z"
      },
      "message": "Fix LOADV/LOADVN refcount printing",
      "tree": {
        "sha": "bff7daeb282547034e7198b0f645e52142a1af11",
        "url": "https://api.github.com/repos/stedolan/jq/git/trees/bff7daeb282547034e7198b0f645e52142a1af11"
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      "comment_count": 0,
      "verification": {
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        "reason": "unsigned",
        "signature": null,
        "payload": null
      }
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    "url": "https://api.github.com/repos/stedolan/jq/commits/1a1804afcb88cdc3f1f0e74e83385146b55ae205",
    "html_url": "https://github.com/stedolan/jq/commit/1a1804afcb88cdc3f1f0e74e83385146b55ae205",
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      "url": "https://api.github.com/users/nicowilliams",
      "html_url": "https://github.com/nicowilliams",
      "followers_url": "https://api.github.com/users/nicowilliams/followers",
      "following_url": "https://api.github.com/users/nicowilliams/following{/other_user}",
      "gists_url": "https://api.github.com/users/nicowilliams/gists{/gist_id}",
      "starred_url": "https://api.github.com/users/nicowilliams/starred{/owner}{/repo}",
      "subscriptions_url": "https://api.github.com/users/nicowilliams/subscriptions",
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      "site_admin": false
    },
    "committer": {
      "login": "nicowilliams",
      "id": 604851,
      "node_id": "MDQ6VXNlcjYwNDg1MQ==",
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      "html_url": "https://github.com/nicowilliams",
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      "following_url": "https://api.github.com/users/nicowilliams/following{/other_user}",
      "gists_url": "https://api.github.com/users/nicowilliams/gists{/gist_id}",
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      "type": "User",
      "site_admin": false
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    "parents": [
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        "url": "https://api.github.com/repos/stedolan/jq/commits/582717a7b4af6ce0e231b9aee090107235ef2d0f",
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    "node_id": "C_kwDOAE3WVdoAKDU4MjcxN2E3YjRhZjZjZTBlMjMxYjlhZWUwOTAxMDcyMzVlZjJkMGY",
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        "name": "Nicolas Williams",
        "email": "nico@cryptonector.com",
        "date": "2021-10-21T05:10:47Z"
      },
      "committer": {
        "name": "Nicolas Williams",
        "email": "nico@cryptonector.com",
        "date": "2021-10-24T21:23:26Z"
      },
      "message": "Fix crash in LOADVN when stack grows\n\nThis `stack_push()` call in LOADVN invalidates `var`:\n\n       jv* var = frame_local_var(jq, v, level);\n       jv_free(stack_popn(jq));\n------>stack_push(jq, *var);\n       *var = jv_null();\n       ^^^^^^\n\nWe have to re-compute `var`:\n\n       jv* var = frame_local_var(jq, v, level);\n       jv_free(stack_popn(jq));\n       stack_push(jq, *var);\n------>var = frame_local_var(jq, v, level);\n       *var = jv_null();",
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      "comment_count": 0,
      "verification": {
        "verified": false,
        "reason": "unsigned",
        "signature": null,
        "payload": null
      }
    },
    "url": "https://api.github.com/repos/stedolan/jq/commits/582717a7b4af6ce0e231b9aee090107235ef2d0f",
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      "following_url": "https://api.github.com/users/nicowilliams/following{/other_user}",
      "gists_url": "https://api.github.com/users/nicowilliams/gists{/gist_id}",
      "starred_url": "https://api.github.com/users/nicowilliams/starred{/owner}{/repo}",
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      "following_url": "https://api.github.com/users/nicowilliams/following{/other_user}",
      "gists_url": "https://api.github.com/users/nicowilliams/gists{/gist_id}",
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      "message": "Appveyor: Get Appveyor building again",
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      "comment_count": 0,
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      "html_url": "https://github.com/nicowilliams",
      "followers_url": "https://api.github.com/users/nicowilliams/followers",
      "following_url": "https://api.github.com/users/nicowilliams/following{/other_user}",
      "gists_url": "https://api.github.com/users/nicowilliams/gists{/gist_id}",
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      "organizations_url": "https://api.github.com/users/nicowilliams/orgs",
      "repos_url": "https://api.github.com/users/nicowilliams/repos",
      "events_url": "https://api.github.com/users/nicowilliams/events{/privacy}",
      "received_events_url": "https://api.github.com/users/nicowilliams/received_events",
      "type": "User",
      "site_admin": false
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    "committer": {
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      "html_url": "https://github.com/nicowilliams",
      "followers_url": "https://api.github.com/users/nicowilliams/followers",
      "following_url": "https://api.github.com/users/nicowilliams/following{/other_user}",
      "gists_url": "https://api.github.com/users/nicowilliams/gists{/gist_id}",
      "starred_url": "https://api.github.com/users/nicowilliams/starred{/owner}{/repo}",
      "subscriptions_url": "https://api.github.com/users/nicowilliams/subscriptions",
      "organizations_url": "https://api.github.com/users/nicowilliams/orgs",
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      "type": "User",
      "site_admin": false
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        "url": "https://api.github.com/repos/stedolan/jq/commits/d79fe7fd582fe0dfdb253445e8ccd671d6fdf8b6",
        "html_url": "https://github.com/stedolan/jq/commit/d79fe7fd582fe0dfdb253445e8ccd671d6fdf8b6"
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]

    2、jq 格式化json

    # 操作
curl 'https://api.github.com/repos/stedolan/jq/commits?per_page=5' | jq '.'

# 响应
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        "date": "2021-10-21T05:17:39Z"
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        "email": "nico@cryptonector.com",
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      "following_url": "https://api.github.com/users/nicowilliams/following{/other_user}",
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        "reason": "unsigned",
        "signature": null,
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  },
  {
    "sha": "07dc653ae151a8320646a1c955839fb88d4a5546",
    "node_id": "C_kwDOAE3WVdoAKDA3ZGM2NTNhZTE1MWE4MzIwNjQ2YTFjOTU1ODM5ZmI4OGQ0YTU1NDY",
    "commit": {
      "author": {
        "name": "Nicolas Williams",
        "email": "nico@cryptonector.com",
        "date": "2021-10-24T20:59:57Z"
      },
      "committer": {
        "name": "Nicolas Williams",
        "email": "nico@cryptonector.com",
        "date": "2021-10-24T21:23:26Z"
      },
      "message": "Appveyor: Get Appveyor building again",
      "tree": {
        "sha": "eb6189c146e19171ae99a80a23e6dd64dc408c1b",
        "url": "https://api.github.com/repos/stedolan/jq/git/trees/eb6189c146e19171ae99a80a23e6dd64dc408c1b"
      },
      "url": "https://api.github.com/repos/stedolan/jq/git/commits/07dc653ae151a8320646a1c955839fb88d4a5546",
      "comment_count": 0,
      "verification": {
        "verified": false,
        "reason": "unsigned",
        "signature": null,
        "payload": null
      }
    },
    "url": "https://api.github.com/repos/stedolan/jq/commits/07dc653ae151a8320646a1c955839fb88d4a5546",
    "html_url": "https://github.com/stedolan/jq/commit/07dc653ae151a8320646a1c955839fb88d4a5546",
    "comments_url": "https://api.github.com/repos/stedolan/jq/commits/07dc653ae151a8320646a1c955839fb88d4a5546/comments",
    "author": {
      "login": "nicowilliams",
      "id": 604851,
      "node_id": "MDQ6VXNlcjYwNDg1MQ==",
      "avatar_url": "https://avatars.githubusercontent.com/u/604851?v=4",
      "gravatar_id": "",
      "url": "https://api.github.com/users/nicowilliams",
      "html_url": "https://github.com/nicowilliams",
      "followers_url": "https://api.github.com/users/nicowilliams/followers",
      "following_url": "https://api.github.com/users/nicowilliams/following{/other_user}",
      "gists_url": "https://api.github.com/users/nicowilliams/gists{/gist_id}",
      "starred_url": "https://api.github.com/users/nicowilliams/starred{/owner}{/repo}",
      "subscriptions_url": "https://api.github.com/users/nicowilliams/subscriptions",
      "organizations_url": "https://api.github.com/users/nicowilliams/orgs",
      "repos_url": "https://api.github.com/users/nicowilliams/repos",
      "events_url": "https://api.github.com/users/nicowilliams/events{/privacy}",
      "received_events_url": "https://api.github.com/users/nicowilliams/received_events",
      "type": "User",
      "site_admin": false
    },
    "committer": {
      "login": "nicowilliams",
      "id": 604851,
      "node_id": "MDQ6VXNlcjYwNDg1MQ==",
      "avatar_url": "https://avatars.githubusercontent.com/u/604851?v=4",
      "gravatar_id": "",
      "url": "https://api.github.com/users/nicowilliams",
      "html_url": "https://github.com/nicowilliams",
      "followers_url": "https://api.github.com/users/nicowilliams/followers",
      "following_url": "https://api.github.com/users/nicowilliams/following{/other_user}",
      "gists_url": "https://api.github.com/users/nicowilliams/gists{/gist_id}",
      "starred_url": "https://api.github.com/users/nicowilliams/starred{/owner}{/repo}",
      "subscriptions_url": "https://api.github.com/users/nicowilliams/subscriptions",
      "organizations_url": "https://api.github.com/users/nicowilliams/orgs",
      "repos_url": "https://api.github.com/users/nicowilliams/repos",
      "events_url": "https://api.github.com/users/nicowilliams/events{/privacy}",
      "received_events_url": "https://api.github.com/users/nicowilliams/received_events",
      "type": "User",
      "site_admin": false
    },
    "parents": [
      {
        "sha": "d79fe7fd582fe0dfdb253445e8ccd671d6fdf8b6",
        "url": "https://api.github.com/repos/stedolan/jq/commits/d79fe7fd582fe0dfdb253445e8ccd671d6fdf8b6",
        "html_url": "https://github.com/stedolan/jq/commit/d79fe7fd582fe0dfdb253445e8ccd671d6fdf8b6"
      }
    ]
  }
]

    3、jq 获取json数组第一个元素

    # 操作
curl 'https://api.github.com/repos/stedolan/jq/commits?per_page=5' | jq '.[0]'

# 响应
{
  "sha": "a9f97e9e61a910a374a5d768244e8ad63f407d3e",
  "node_id": "C_kwDOAE3WVdoAKGE5Zjk3ZTllNjFhOTEwYTM3NGE1ZDc2ODI0NGU4YWQ2M2Y0MDdkM2U",
  "commit": {
    "author": {
      "name": "Nicolas Williams",
      "email": "nico@cryptonector.com",
      "date": "2021-10-21T05:17:39Z"
    },
    "committer": {
      "name": "Nicolas Williams",
      "email": "nico@cryptonector.com",
      "date": "2021-10-24T21:23:26Z"
    },
    "message": "Fix accidentally quadratic behavior in _modify\n\nWe need to be careful to not grab an extra reference when mutating data\nstructures because that means we make extra copies.  Doing that every\ntime in `_modify` is really painful, as that function implements `|=`\nand all modify-assign operators.\n\n`jv_setpath()` also grabs additional references, so this is not the only\nfix needed for the modify-assign operators to not be accidentally\nquadratic.\n\nWe have to use `LOADVN` in order to make this fix possible, so we should\nreally byte-code `_modify` rather than jq-code it.  However, as a\nstop-gap to make this fix easier, I'm adding syntax for referring to a\n`$binding` such that you get `LOADVN` instead of `LOADV`.\n\nThis syntax is not meant to be used outside jq's internals!  Therefore\nit is not documented.  I promise to break it later, so don't use it!\n\nTBD, but later:\n\n - Optimize `_modify` for the case where `update` outputs more than one\n   value.\n\n   This is trivial: add a `setpath($p; null)` in the middle of `_modify`\n   before calling `update`.  But unfortunately the VM retains a\n   reference to `value_at_path` for path expression checking, and fixing\n   that will require more work.",
    "tree": {
      "sha": "7883361d86bd97b1bcd2299fa5886182b27cee54",
      "url": "https://api.github.com/repos/stedolan/jq/git/trees/7883361d86bd97b1bcd2299fa5886182b27cee54"
    },
    "url": "https://api.github.com/repos/stedolan/jq/git/commits/a9f97e9e61a910a374a5d768244e8ad63f407d3e",
    "comment_count": 0,
    "verification": {
      "verified": false,
      "reason": "unsigned",
      "signature": null,
      "payload": null
    }
  },
  "url": "https://api.github.com/repos/stedolan/jq/commits/a9f97e9e61a910a374a5d768244e8ad63f407d3e",
  "html_url": "https://github.com/stedolan/jq/commit/a9f97e9e61a910a374a5d768244e8ad63f407d3e",
  "comments_url": "https://api.github.com/repos/stedolan/jq/commits/a9f97e9e61a910a374a5d768244e8ad63f407d3e/comments",
  "author": {
    "login": "nicowilliams",
    "id": 604851,
    "node_id": "MDQ6VXNlcjYwNDg1MQ==",
    "avatar_url": "https://avatars.githubusercontent.com/u/604851?v=4",
    "gravatar_id": "",
    "url": "https://api.github.com/users/nicowilliams",
    "html_url": "https://github.com/nicowilliams",
    "followers_url": "https://api.github.com/users/nicowilliams/followers",
    "following_url": "https://api.github.com/users/nicowilliams/following{/other_user}",
    "gists_url": "https://api.github.com/users/nicowilliams/gists{/gist_id}",
    "starred_url": "https://api.github.com/users/nicowilliams/starred{/owner}{/repo}",
    "subscriptions_url": "https://api.github.com/users/nicowilliams/subscriptions",
    "organizations_url": "https://api.github.com/users/nicowilliams/orgs",
    "repos_url": "https://api.github.com/users/nicowilliams/repos",
    "events_url": "https://api.github.com/users/nicowilliams/events{/privacy}",
    "received_events_url": "https://api.github.com/users/nicowilliams/received_events",
    "type": "User",
    "site_admin": false
  },
  "committer": {
    "login": "nicowilliams",
    "id": 604851,
    "node_id": "MDQ6VXNlcjYwNDg1MQ==",
    "avatar_url": "https://avatars.githubusercontent.com/u/604851?v=4",
    "gravatar_id": "",
    "url": "https://api.github.com/users/nicowilliams",
    "html_url": "https://github.com/nicowilliams",
    "followers_url": "https://api.github.com/users/nicowilliams/followers",
    "following_url": "https://api.github.com/users/nicowilliams/following{/other_user}",
    "gists_url": "https://api.github.com/users/nicowilliams/gists{/gist_id}",
    "starred_url": "https://api.github.com/users/nicowilliams/starred{/owner}{/repo}",
    "subscriptions_url": "https://api.github.com/users/nicowilliams/subscriptions",
    "organizations_url": "https://api.github.com/users/nicowilliams/orgs",
    "repos_url": "https://api.github.com/users/nicowilliams/repos",
    "events_url": "https://api.github.com/users/nicowilliams/events{/privacy}",
    "received_events_url": "https://api.github.com/users/nicowilliams/received_events",
    "type": "User",
    "site_admin": false
  },
  "parents": [
    {
      "sha": "0c3455d3290fa03da8c01c135dd7126a80ed28a8",
      "url": "https://api.github.com/repos/stedolan/jq/commits/0c3455d3290fa03da8c01c135dd7126a80ed28a8",
      "html_url": "https://github.com/stedolan/jq/commit/0c3455d3290fa03da8c01c135dd7126a80ed28a8"
    }
  ]
}

    4、jq 获取json指定元素的指定字段

    # 操作
curl 'https://api.github.com/repos/stedolan/jq/commits?per_page=5' | jq '.[0] | {message: .commit.message, name: .commit.committer.name}'

# 响应
{
  "message": "Fix accidentally quadratic behavior in _modify\n\nWe need to be careful to not grab an extra reference when mutating data\nstructures because that means we make extra copies.  Doing that every\ntime in `_modify` is really painful, as that function implements `|=`\nand all modify-assign operators.\n\n`jv_setpath()` also grabs additional references, so this is not the only\nfix needed for the modify-assign operators to not be accidentally\nquadratic.\n\nWe have to use `LOADVN` in order to make this fix possible, so we should\nreally byte-code `_modify` rather than jq-code it.  However, as a\nstop-gap to make this fix easier, I'm adding syntax for referring to a\n`$binding` such that you get `LOADVN` instead of `LOADV`.\n\nThis syntax is not meant to be used outside jq's internals!  Therefore\nit is not documented.  I promise to break it later, so don't use it!\n\nTBD, but later:\n\n - Optimize `_modify` for the case where `update` outputs more than one\n   value.\n\n   This is trivial: add a `setpath($p; null)` in the middle of `_modify`\n   before calling `update`.  But unfortunately the VM retains a\n   reference to `value_at_path` for path expression checking, and fixing\n   that will require more work.",
  "name": "Nicolas Williams"
}

    5、jq获取json数组中所有的指定字段

    # 操作
curl 'https://api.github.com/repos/stedolan/jq/commits?per_page=5' | jq '.[] | {message: .commit.message, name: .commit.committer.name}'

# 响应
{
  "message": "Fix accidentally quadratic behavior in _modify\n\nWe need to be careful to not grab an extra reference when mutating data\nstructures because that means we make extra copies.  Doing that every\ntime in `_modify` is really painful, as that function implements `|=`\nand all modify-assign operators.\n\n`jv_setpath()` also grabs additional references, so this is not the only\nfix needed for the modify-assign operators to not be accidentally\nquadratic.\n\nWe have to use `LOADVN` in order to make this fix possible, so we should\nreally byte-code `_modify` rather than jq-code it.  However, as a\nstop-gap to make this fix easier, I'm adding syntax for referring to a\n`$binding` such that you get `LOADVN` instead of `LOADV`.\n\nThis syntax is not meant to be used outside jq's internals!  Therefore\nit is not documented.  I promise to break it later, so don't use it!\n\nTBD, but later:\n\n - Optimize `_modify` for the case where `update` outputs more than one\n   value.\n\n   This is trivial: add a `setpath($p; null)` in the middle of `_modify`\n   before calling `update`.  But unfortunately the VM retains a\n   reference to `value_at_path` for path expression checking, and fixing\n   that will require more work.",
  "name": "Nicolas Williams"
}
{
  "message": "Fix accidentally quadratic behavior in setpath\n\nWe need to be careful to not grab an extra reference when mutating\ndata structures because that means we make extra copies.  Doing that\nevery time in `jv_setpath()` is really painful, as that function is used\nin `_modify/2`, which is used in `|=` and all modify-assign operators.\n\n`_modify` also grabs additional references, so this is not the only fix\nneeded for the modify-assign operators to not be accidentally quadratic.",
  "name": "Nicolas Williams"
}
{
  "message": "Fix LOADV/LOADVN refcount printing",
  "name": "Nicolas Williams"
}
{
  "message": "Fix crash in LOADVN when stack grows\n\nThis `stack_push()` call in LOADVN invalidates `var`:\n\n       jv* var = frame_local_var(jq, v, level);\n       jv_free(stack_popn(jq));\n------>stack_push(jq, *var);\n       *var = jv_null();\n       ^^^^^^\n\nWe have to re-compute `var`:\n\n       jv* var = frame_local_var(jq, v, level);\n       jv_free(stack_popn(jq));\n       stack_push(jq, *var);\n------>var = frame_local_var(jq, v, level);\n       *var = jv_null();",
  "name": "Nicolas Williams"
}
{
  "message": "Appveyor: Get Appveyor building again",
  "name": "Nicolas Williams"
}

    6、jq获取json数组中所有的指定字段并存入数组

    # 操作
curl 'https://api.github.com/repos/stedolan/jq/commits?per_page=5' | jq '[.[] | {message: .commit.message, name: .commit.committer.name}]'

# 响应
[
  {
    "message": "Fix accidentally quadratic behavior in _modify\n\nWe need to be careful to not grab an extra reference when mutating data\nstructures because that means we make extra copies.  Doing that every\ntime in `_modify` is really painful, as that function implements `|=`\nand all modify-assign operators.\n\n`jv_setpath()` also grabs additional references, so this is not the only\nfix needed for the modify-assign operators to not be accidentally\nquadratic.\n\nWe have to use `LOADVN` in order to make this fix possible, so we should\nreally byte-code `_modify` rather than jq-code it.  However, as a\nstop-gap to make this fix easier, I'm adding syntax for referring to a\n`$binding` such that you get `LOADVN` instead of `LOADV`.\n\nThis syntax is not meant to be used outside jq's internals!  Therefore\nit is not documented.  I promise to break it later, so don't use it!\n\nTBD, but later:\n\n - Optimize `_modify` for the case where `update` outputs more than one\n   value.\n\n   This is trivial: add a `setpath($p; null)` in the middle of `_modify`\n   before calling `update`.  But unfortunately the VM retains a\n   reference to `value_at_path` for path expression checking, and fixing\n   that will require more work.",
    "name": "Nicolas Williams"
  },
  {
    "message": "Fix accidentally quadratic behavior in setpath\n\nWe need to be careful to not grab an extra reference when mutating\ndata structures because that means we make extra copies.  Doing that\nevery time in `jv_setpath()` is really painful, as that function is used\nin `_modify/2`, which is used in `|=` and all modify-assign operators.\n\n`_modify` also grabs additional references, so this is not the only fix\nneeded for the modify-assign operators to not be accidentally quadratic.",
    "name": "Nicolas Williams"
  },
  {
    "message": "Fix LOADV/LOADVN refcount printing",
    "name": "Nicolas Williams"
  },
  {
    "message": "Fix crash in LOADVN when stack grows\n\nThis `stack_push()` call in LOADVN invalidates `var`:\n\n       jv* var = frame_local_var(jq, v, level);\n       jv_free(stack_popn(jq));\n------>stack_push(jq, *var);\n       *var = jv_null();\n       ^^^^^^\n\nWe have to re-compute `var`:\n\n       jv* var = frame_local_var(jq, v, level);\n       jv_free(stack_popn(jq));\n       stack_push(jq, *var);\n------>var = frame_local_var(jq, v, level);\n       *var = jv_null();",
    "name": "Nicolas Williams"
  },
  {
    "message": "Appveyor: Get Appveyor building again",
    "name": "Nicolas Williams"
  }
]

    7、jq高级用法

    curl 'https://api.github.com/repos/stedolan/jq/commits?per_page=5' | jq '[.[] | {message: .commit.message, name: .commit.committer.name, parents: [.parents[].html_url]}]' 

# 响应
[
  {
    "message": "Fix accidentally quadratic behavior in _modify\n\nWe need to be careful to not grab an extra reference when mutating data\nstructures because that means we make extra copies.  Doing that every\ntime in `_modify` is really painful, as that function implements `|=`\nand all modify-assign operators.\n\n`jv_setpath()` also grabs additional references, so this is not the only\nfix needed for the modify-assign operators to not be accidentally\nquadratic.\n\nWe have to use `LOADVN` in order to make this fix possible, so we should\nreally byte-code `_modify` rather than jq-code it.  However, as a\nstop-gap to make this fix easier, I'm adding syntax for referring to a\n`$binding` such that you get `LOADVN` instead of `LOADV`.\n\nThis syntax is not meant to be used outside jq's internals!  Therefore\nit is not documented.  I promise to break it later, so don't use it!\n\nTBD, but later:\n\n - Optimize `_modify` for the case where `update` outputs more than one\n   value.\n\n   This is trivial: add a `setpath($p; null)` in the middle of `_modify`\n   before calling `update`.  But unfortunately the VM retains a\n   reference to `value_at_path` for path expression checking, and fixing\n   that will require more work.",
    "name": "Nicolas Williams",
    "parents": [
      "https://github.com/stedolan/jq/commit/0c3455d3290fa03da8c01c135dd7126a80ed28a8"
    ]
  },
  {
    "message": "Fix accidentally quadratic behavior in setpath\n\nWe need to be careful to not grab an extra reference when mutating\ndata structures because that means we make extra copies.  Doing that\nevery time in `jv_setpath()` is really painful, as that function is used\nin `_modify/2`, which is used in `|=` and all modify-assign operators.\n\n`_modify` also grabs additional references, so this is not the only fix\nneeded for the modify-assign operators to not be accidentally quadratic.",
    "name": "Nicolas Williams",
    "parents": [
      "https://github.com/stedolan/jq/commit/1a1804afcb88cdc3f1f0e74e83385146b55ae205"
    ]
  },
  {
    "message": "Fix LOADV/LOADVN refcount printing",
    "name": "Nicolas Williams",
    "parents": [
      "https://github.com/stedolan/jq/commit/582717a7b4af6ce0e231b9aee090107235ef2d0f"
    ]
  },
  {
    "message": "Fix crash in LOADVN when stack grows\n\nThis `stack_push()` call in LOADVN invalidates `var`:\n\n       jv* var = frame_local_var(jq, v, level);\n       jv_free(stack_popn(jq));\n------>stack_push(jq, *var);\n       *var = jv_null();\n       ^^^^^^\n\nWe have to re-compute `var`:\n\n       jv* var = frame_local_var(jq, v, level);\n       jv_free(stack_popn(jq));\n       stack_push(jq, *var);\n------>var = frame_local_var(jq, v, level);\n       *var = jv_null();",
    "name": "Nicolas Williams",
    "parents": [
      "https://github.com/stedolan/jq/commit/07dc653ae151a8320646a1c955839fb88d4a5546"
    ]
  },
  {
    "message": "Appveyor: Get Appveyor building again",
    "name": "Nicolas Williams",
    "parents": [
      "https://github.com/stedolan/jq/commit/d79fe7fd582fe0dfdb253445e8ccd671d6fdf8b6"
    ]
  }
]

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