Outputting a list of variables to `json` or `yaml` using `column` and `goyq`

Quick little command line kung fu job with this parser called column

 column -h

 column [options] [<file>...]

Columnate lists.

 -t, --table                      create a table
 -n, --table-name <name>          table name for JSON output
 -O, --table-order <columns>      specify order of output columns
 -C, --table-column <properties>  define column
 -N, --table-columns <names>      comma separated columns names
 -l, --table-columns-limit <num>  maximal number of input columns
 -E, --table-noextreme <columns>  don't count long text from the columns to column width
 -d, --table-noheadings           don't print header
 -m, --table-maxout               fill all available space
 -e, --table-header-repeat        repeat header for each page
 -H, --table-hide <columns>       don't print the columns
 -R, --table-right <columns>      right align text in these columns
 -T, --table-truncate <columns>   truncate text in the columns when necessary
 -W, --table-wrap <columns>       wrap text in the columns when necessary
 -L, --keep-empty-lines           don't ignore empty lines
 -J, --json                       use JSON output format for table

 -r, --tree <column>              column to use tree-like output for the table
 -i, --tree-id <column>           line ID to specify child-parent relation
 -p, --tree-parent <column>       parent to specify child-parent relation

 -c, --output-width <width>       width of output in number of characters
 -o, --output-separator <string>  columns separator for table output (default is two spaces)
 -s, --separator <string>         possible table delimiters
 -x, --fillrows                   fill rows before columns

 -h, --help                       display this help
 -V, --version                    display version

For more details see column(1).

It’s in the util-linux package, which, if I am remembering correctly, is included by default in basically any release outside of netboot and cloud images

 pacman -Qi util-linux
Name            : util-linux
Version         : 2.40.1-1
Description     : Miscellaneous system utilities for Linux
Architecture    : x86_64
URL             : https://github.com/util-linux/util-linux
Licenses        : BSD-2-Clause  BSD-3-Clause  BSD-4-Clause-UC  GPL-2.0-only
                  GPL-2.0-or-later  GPL-3.0-or-later  ISC  LGPL-2.1-or-later
Groups          : None
Provides        : rfkill  hardlink
Depends On      : util-linux-libs=2.40.1  coreutils  file  libmagic.so=1-64
                  glibc  libcap-ng  libxcrypt  libcrypt.so=2-64  ncurses
                  libncursesw.so=6-64  pam  readline  shadow  systemd-libs
                  libsystemd.so=0-64  libudev.so=1-64  zlib
Optional Deps   : words: default dictionary for look
Required By     : apr  arch-install-scripts  base  devtools  dracut  f2fs-tools
                  fakeroot  inxi  jfsutils  keycloak  libewf  nilfs-utils
                  ntfsprogs-ntfs3  nvme-cli  ostree  quickemu  reiserfsprogs
                  sbctl  systemd  zeromq
Optional For    : e2fsprogs  gzip  syslinux
Conflicts With  : rfkill  hardlink
Replaces        : rfkill  hardlink
Installed Size  : 14.47 MiB
Packager        : Christian Hesse <eworm@archlinux.org>
Build Date      : Mon 06 May 2024 12:22:23 PM PDT
Install Date    : Wed 08 May 2024 09:27:41 AM PDT
Install Reason  : Installed as a dependency for another package
Install Script  : No
Validated By    : Signature

this demonstrates why it’s included: It’s required by basically all of the setup infrastructure packages (makes sense). But I don’t really see column getting a lot of attention. Not sure why.

Here I used it to convert a list of installed flatpak containers to both JSON and YAML, using the column names from the flatpak’s output options (see flatpak list --help for available columns).

Start by making a list using the flatpak list --columns=$COLUMNS command:

# export comma-separated column headers, in desired order
export COLUMNS='name,application,version,branch,arch,origin,installation,ref'

# make a list of flatpaks with these columns
flatpak list --app --columns=$NAMES > all-flatpak-apps.list

# verify the list was created
cat all-flatpak-apps.list

# output (truncated):
Delta Chat	chat.delta.desktop	v1.44.1	stable	x86_64	flathub	user	chat.delta.desktop/x86_64/stable
Twilio Authy	com.authy.Authy	2.5.0	stable	x86_64	flathub	user	com.authy.Authy/x86_64/stable
Discord	com.discordapp.Discord	0.0.54	stable	x86_64	flathub	user	com.discordapp.Discord/x86_64/stable
GitButler	com.gitbutler.gitbutler	0.11.7	stable	x86_64	flathub	user	com.gitbutler.gitbutler/x86_64/stable
Drawing	com.github.maoschanz.drawing	1.0.2	stable	x86_64	flathub	user	com.github.maoschanz.drawing/x86_64/stable
Flatseal	com.github.tchx84.Flatseal	2.2.0	stable	x86_64	flathub	user	com.github.tchx84.Flatseal/x86_64/stable
Extension Manager	com.mattjakeman.ExtensionManager	0.5.1	stable	x86_64	flathub	user	com.mattjakeman.ExtensionManager/x86_64/stable
Yubico Authenticator	com.yubico.yubioath	7.0.0	stable	x86_64	flathub	user	com.yubico.yubioath/x86_64/stable
. . . 

It’s kinda hard to read like that, but I suppose if your font were small enough, or the terminal wide enough, the lines would stop wrapping and they’d be easier to read…

Then, take the list and convert it to json with a little column parsing:

# the flags are: 
# 1. create a table (-t), 
# 2. give it these headers (-N $comma,separated,headervals) 
# 3. limit it to the number we gave you (-l $integer)
# 4. make it json! (-J)
column -t -d -N $NAMES -l 8 -J all-flatpak-apps.list > flatpak-apps.json

# column is a lot more forgiving of formatting than jq and yq

I haven’t had a lot of luck piping to column directly to make a parse-inception one-liner, which is why I am making two files (the flatpak.list and the .json file). I am sure there’s some people out there who could make this work, but I want to keep it on the less complicated side for demonstrative purposes, as well.

The output will be json format with the column parse by itself, but some of us like to pretty-print our json with jq , since the colors make it easier to read – especially when they’re not even pretty-printed:

column -t -d -N $NAMES -l 8 -J all-flatpak-apps.list | jq  

  "table": [
      "name": "Delta",
      "application": "Chat",
      "version": "chat.delta.desktop",
      "branch": "v1.44.1",
      "arch": "stable",
      "origin": "x86_64",
      "installation": "flathub",
      "ref": "user\tchat.delta.desktop/x86_64/stable"
      "name": "Twilio",
      "application": "Authy",
      "version": "com.authy.Authy",
      "branch": "2.5.0",
      "arch": "stable",
      "origin": "x86_64",
      "installation": "flathub",
      "ref": "user\tcom.authy.Authy/x86_64/stable"

      "name": "UPnP",
      "application": "Router",
      "version": "Control",
      "branch": "org.upnproutercontrol.UPnPRouterControl",
      "arch": "0.3.4",
      "origin": "stable",
      "installation": "x86_64",
      "ref": "flathub\tuser\torg.upnproutercontrol.UPnPRouterControl/x86_64/stable"
      "name": "Wireshark",
      "application": "org.wireshark.Wireshark",
      "version": "4.2.5",
      "branch": "stable",
      "arch": "x86_64",
      "origin": "flathub",
      "installation": "user",
      "ref": "org.wireshark.Wireshark/x86_64/stable"
      "name": "ZAP",
      "application": "org.zaproxy.ZAP",
      "version": "2.15.0",
      "branch": "stable",
      "arch": "x86_64",
      "origin": "flathub",
      "installation": "user",
      "ref": "org.zaproxy.ZAP/x86_64/stable"

And if you need yaml, the same thing works with yq:

# what NOT to do (if you want to be able to read it):

column -t -d -N $NAMES -l 8 -J all-flatpak-apps.list | yq
{"table": [{"name": "Delta", "application": "Chat", "version": "chat.delta.desktop", "branch": "v1.44.1", "arch": "stable", "origin": "x86_64", "installation": "flathub", "ref": "user\tchat.delta.desktop/x86_64/stable"}, {"name": "Twilio", "application": "Authy", . . . 

# sometimes yq requires being super-explicit:

# yq flags are: 
# 1. input file type (-p type)
# 2. output file type (-o type)
# 3. pretty-print (-P) 
column -t -d -N $NAMES -l 8 -J all-flatpak-apps.list | yq -p json -o yaml -P
  - name: Delta
    application: Chat
    version: chat.delta.desktop
    branch: v1.44.1
    arch: stable
    origin: x86_64
    installation: flathub
    ref: "user\tchat.delta.desktop/x86_64/stable"
  - name: Twilio
    application: Authy
    version: com.authy.Authy
    branch: 2.5.0
    arch: stable
    origin: x86_64
    installation: flathub
    ref: "user\tcom.authy.Authy/x86_64/stable"
  - name: Discord
    application: com.discordapp.Discord
    version: 0.0.54
    branch: stable
    arch: x86_64
    origin: flathub
    installation: user
    ref: com.discordapp.Discord/x86_64/stable
. . . 

I’ve got the go-yq package, which has a much newer version of jq included with it, so if you’re seeing some differences in behavior or command-line arguments, that could be why – give it a shot if you’re having issues. (I do prefer the original jq, but I don’t really have a choice since it’s a dependency of devtools

# not a huge fan of gojq-bin, but go-yq is awesome...
 pacman -Qi go-yq
Name            : go-yq
Version         : 4.44.1-1
Description     : Portable command-line YAML processor
Architecture    : x86_64
URL             : https://github.com/mikefarah/yq
Licenses        : MIT
Groups          : None
Provides        : None
Depends On      : glibc
Optional Deps   : None
Required By     : None
Optional For    : None
Conflicts With  : yq
Replaces        : None
Installed Size  : 9.58 MiB
Packager        : Daniel M. Capella <polyzen@archlinux.org>
Build Date      : Sat 11 May 2024 08:14:21 PM PDT
Install Date    : Sat 11 May 2024 09:08:38 PM PDT
Install Reason  : Explicitly installed
Install Script  : No
Validated By    : Signature

And don’t forget, column should be able to format basically any time of list with repeating columns. I guess that’s all for now, enjoy!

ok nevermind, just one more thing: This has nothing to do with column, necessarily, but it’s all the output you can get when you choose json as your output. I’ll have to do another post about this, but it’s tangentially related.

Look at the output from kubernetes kubectl get pods -A :

kubectl get pods -A
NAMESPACE              NAME                                        READY   STATUS    RESTARTS       AGE
default                elasticsearch-coordinating-0                1/1     Running   0              91m
default                elasticsearch-coordinating-1                1/1     Running   0              91m
default                elasticsearch-data-0                        1/1     Running   0              91m
default                elasticsearch-data-1                        1/1     Running   0              91m
default                elasticsearch-ingest-0                      1/1     Running   0              91m
default                elasticsearch-ingest-1                      1/1     Running   0              91m
default                elasticsearch-master-0                      1/1     Running   0              91m
default                elasticsearch-master-1                      1/1     Running   0              91m
kube-system            coredns-7db6d8ff4d-x8nnb                    1/1     Running   1 (101m ago)   125m
kube-system            etcd-minikube                               1/1     Running   1 (101m ago)   125m
kube-system            kube-apiserver-minikube                     1/1     Running   1 (101m ago)   125m
kube-system            kube-controller-manager-minikube            1/1     Running   1 (101m ago)   125m
kube-system            kube-proxy-jbds4                            1/1     Running   1 (101m ago)   125m
kube-system            kube-scheduler-minikube                     1/1     Running   1 (101m ago)   125m
kube-system            metrics-server-c59844bb4-d8wnd              1/1     Running   1 (101m ago)   119m
kube-system            storage-provisioner                         1/1     Running   3 (101m ago)   125m
kubernetes-dashboard   dashboard-metrics-scraper-b5fc48f67-j5znq   1/1     Running   1 (101m ago)   121m
kubernetes-dashboard   kubernetes-dashboard-779776cb65-rh8s2       1/1     Running   2 (101m ago)   121m
portainer              portainer-7bf545c674-xnjjr                  1/1     Running   1 (101m ago)   119m
yakd-dashboard         yakd-dashboard-5ddbf7d777-mzqk2             1/1     Running   1 (101m ago)   119m

It’s not bad, but check out all the info you get when you add --output json:

# +`jq` to colorize the output (or `yq -p json -o json -P`)
kubectl get pods -A -o json | jq 
  "apiVersion": "v1",
  "items": [
      "apiVersion": "v1",
      "kind": "Pod",
      "metadata": {
        "creationTimestamp": "2024-05-25T12:26:56Z",
        "generateName": "elasticsearch-coordinating-",
        "labels": {
          "app": "coordinating-only",
          "app.kubernetes.io/component": "coordinating-only",
          "app.kubernetes.io/instance": "elasticsearch",
          "app.kubernetes.io/managed-by": "Helm",
          "app.kubernetes.io/name": "elasticsearch",
          "app.kubernetes.io/version": "8.13.4",
          "apps.kubernetes.io/pod-index": "0",
          "controller-revision-hash": "elasticsearch-coordinating-64759546b",
          "helm.sh/chart": "elasticsearch-21.1.0",
          "statefulset.kubernetes.io/pod-name": "elasticsearch-coordinating-0"
        "name": "elasticsearch-coordinating-0",
        "namespace": "default",
        "ownerReferences": [
            "apiVersion": "apps/v1",
            "blockOwnerDeletion": true,
            "controller": true,
            "kind": "StatefulSet",
            "name": "elasticsearch-coordinating",
            "uid": "e403f4a1-3058-4830-8f4e-25323fa68be5"
        "resourceVersion": "2737",
        "uid": "5c26ea5d-5ec7-40b1-946c-573651123552"
      "spec": {
        "affinity": {},
        "automountServiceAccountToken": false,
        "containers": [
            "env": [
                "name": "MY_POD_NAME",
                "valueFrom": {
                  "fieldRef": {
                    "apiVersion": "v1",
                    "fieldPath": "metadata.name"
                "name": "BITNAMI_DEBUG",
                "value": "false"
                "name": "ELASTICSEARCH_CLUSTER_NAME",
                "value": "elastic"
                "name": "ELASTICSEARCH_IS_DEDICATED_NODE",
                "value": "yes"
                "name": "ELASTICSEARCH_NODE_ROLES"
                "value": "9300"
                "name": "ELASTICSEARCH_HTTP_PORT_NUMBER",
                "value": "9200"
                "name": "ELASTICSEARCH_CLUSTER_HOSTS",
                "value": "elasticsearch-master-hl.default.svc.cluster.local,elasticsearch-coordinating-hl.default.svc.cluster.local,elasticsearch-data-hl.default.svc.cluster.local,elasticsearch-ingest-hl.default.svc.cluster.local,"
                "name": "ELASTICSEARCH_TOTAL_NODES",
               . . . 

It’s nice that kubectl actually has a yaml output, since it’s a little easier to read than json, what with all the [{"punctuation": "on"},{"basically": "every}, {"word": true}], but most programs, if they even offer json, probably aren’t going to offer yaml – so to convert it, here’s the pipe string:

# adding `yq` colorizes output to `yaml` output, too
kubectl get pods -A -o json | yq -p json -o yaml -P  
apiVersion: v1
  - apiVersion: v1
    kind: Pod
      creationTimestamp: "2024-05-25T12:26:56Z"
      generateName: elasticsearch-coordinating-
        app: coordinating-only
        app.kubernetes.io/component: coordinating-only
        app.kubernetes.io/instance: elasticsearch
        app.kubernetes.io/managed-by: Helm
        app.kubernetes.io/name: elasticsearch
        app.kubernetes.io/version: 8.13.4
        apps.kubernetes.io/pod-index: "0"
        controller-revision-hash: elasticsearch-coordinating-64759546b
        helm.sh/chart: elasticsearch-21.1.0
        statefulset.kubernetes.io/pod-name: elasticsearch-coordinating-0
      name: elasticsearch-coordinating-0
      namespace: default
        - apiVersion: apps/v1
          blockOwnerDeletion: true
          controller: true
          kind: StatefulSet
          name: elasticsearch-coordinating
          uid: e403f4a1-3058-4830-8f4e-25323fa68be5
      resourceVersion: "2737"
      uid: 5c26ea5d-5ec7-40b1-946c-573651123552
      affinity: {}
      automountServiceAccountToken: false
        - env:
            - name: MY_POD_NAME
                  apiVersion: v1
                  fieldPath: metadata.name
            - name: BITNAMI_DEBUG
              value: "false"
              value: elastic
              value: "yes"
            - name: ELASTICSEARCH_NODE_ROLES
              value: "9300"
              value: "9200"
              value: elasticsearch-master-hl.default.svc.cluster.local,elasticsearch-coordinating-hl.default.svc.cluster.local,elasticsearch-data-hl.default.svc.cluster.local,elasticsearch-ingest-hl.default.svc.cluster.local,
              value: "4"
              value: elasticsearch-master-0 elasticsearch-master-1
              value: "2"
              value: $(MY_POD_NAME).elasticsearch-coordinating-hl.default.svc.cluster.local
            - name: ELASTICSEARCH_HEAP_SIZE
              value: 128m
          image: docker.io/bitnami/elasticsearch:8.13.4-debian-12-r0
          imagePullPolicy: IfNotPresent
            failureThreshold: 5
            initialDelaySeconds: 180
            periodSeconds: 10
            successThreshold: 1
              port: rest-api
            timeoutSeconds: 5
          name: elasticsearch
            - containerPort: 9200
              name: rest-api
              protocol: TCP
            - containerPort: 9300
              name: transport
              protocol: TCP
                - /opt/bitnami/scripts/elasticsearch/healthcheck.sh
            failureThreshold: 5
            initialDelaySeconds: 90
            periodSeconds: 10
            successThreshold: 1
            timeoutSeconds: 5
              cpu: 750m
              ephemeral-storage: 1Gi
              memory: 768Mi
              cpu: 500m
              ephemeral-storage: 50Mi
              memory: 512Mi
            allowPrivilegeEscalation: false
                - ALL
            privileged: false
            readOnlyRootFilesystem: true
            runAsGroup: 1001
            runAsNonRoot: true
            runAsUser: 1001
            seLinuxOptions: {}
              type: RuntimeDefault
          terminationMessagePath: /dev/termination-log
          terminationMessagePolicy: File
            - mountPath: /tmp
              name: empty-dir
              subPath: tmp-dir
            - mountPath: /opt/bitnami/elasticsearch/config
              name: empty-dir
              subPath: app-conf-dir
              . . . 

It sure is nice to be able to read the stuff that comes out of the tools we’re using every day…

Author: Avery Freeman

MBA / Audio Engineering alumnus enjoys taking adjunct courses in data sciences, management, and software development. Passionate about collaboratively improving humanity through open source information ecosystems. Tenaciously solves problems of near-universally intolerable tediousness. Proficient in SQL, Python, Javascript, has forgotten SAS, and misses OpenSolaris. Eminently effervescent about Unix-like operating systems and software defined networks, including an unmistakable urge to Berkeley packet filter all the things. Fanatically fond of zfs and linux volume manager. Has lived in Tokyo, SF, Oakland, and now Seattle. Can't forget cooking, hiking, gardening, and playing with your cat.

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