Tips and Tricks

Generic Converters

jc comes with a few generic or standard-format converters, including:

• ASCII (and Unicode) Tables
• Multi-line ASCII (and Unicode) Tables
• CSV
• INI
• Key/Value
• XML
• YAML

Sometimes commands will output in one of these supported formats for easy conversion to JSON.

For example, you can parse the HTTP headers from curl using the Key/Value parser:

$ curl --silent --header "origin: https://origin.example.com" \
       --request GET "https://cors-test.appspot.com/test" \
       --head | jc --kv -p
{
  "http/2 200": "",
  "cache-control": "no-cache",
  "access-control-allow-origin": "https://origin.example.com",
  "access-control-max-age": "0",
  "access-control-allow-credentials": "true",
  "set-cookie": "test=test",
  "expires": "Fri, 01 Jan 1990 00:00:00 GMT",
  "content-type": "application/json",
  "x-cloud-trace-context": "086f2570a400102ed316c10f1719c87e",
  "date": "Tue, 17 May 2022 21:39:06 GMT",
  "server": "Google Frontend",
  "content-length": "15",
  "alt-svc": "h3=\":443\"; ma=2592000,h3-29=\":443\"; ma=2592000,h3-Q050=\":443\"; ma=2592000,h3-Q046=\":443\"; ma=2592000,h3-Q043=\":443\"; ma=2592000,quic=\":443\"; ma=2592000; v=\"46,43\""
}

Alternative JSON Output

Most parsers have slightly different output when using the -r (Raw) cli option. The Raw output is typically used for troubleshooting or in cases where you don't want string to integer/float/bool conversions or even some calculated timestamp fields.

A couple parsers will output significantly different styles of JSON if the Raw option is used:

• env
• history

For example, the env parser turns each environment variable into its own JSON object and adds all of these objects to a list:

$ env | jc --env -p
[
  {
    "name": "TERM_PROGRAM",
    "value": "Apple_Terminal"
  },
  {
    "name": "SHELL",
    "value": "/bin/bash"
  },
  {
    "name": "TERM",
    "value": "xterm-256color"
  },
...
]

This output makes it easy to iterate over each key/value pair and match values to predictable key names. But if you don't need that format, try the -r option:

$ env | jc --env -p -r
{
  "TERM_PROGRAM": "Apple_Terminal",
  "SHELL": "/bin/bash",
  "TERM": "xterm-256color",
...
}

With this output there is no list to iterate over - If you know the name of the key, you can quickly get the value.

The history parser is similar:

$ history | jc --history -p
[
  {
    "line": 1009,
    "command": "jc git log | jq"
  },
  {
    "line": 1010,
    "command": "jc git log --format=full | jq"
  },
  {
    "line": 1011,
    "command": "jc git log --format=fuller --stat | jq"
  },
  {
    "line": 1012,
    "command": "jc git log --format=oneline --shortstat | jq"
  }
]
...

vs.

$ history | jc --history -p -r
{
  "1009": "jc git log | jq",
  "1010": "jc git log --format=full | jq",
  "1011": "jc git log --format=fuller --stat | jq",
  "1012": "jc git log --format=oneline --shortstat | jq"
}