Using jc Command to Convert Command Output to JSON (with examples)
The jc command is a powerful utility that allows users to easily convert the output of various commands to JSON format. This is particularly useful when working with structured data as JSON is a widely supported format for data interchange.
In this article, we will explore 8 different use cases of the jc command, providing code examples and explanations for each one. By the end, you should have a good understanding of how to leverage jc for converting command output to JSON.
Use Case 1: Convert command output to JSON via pipe
To convert the output of a command to JSON using the jc command, you can simply pipe the command’s output to jc followed by the command’s name. Here’s an example:
ifconfig | jc --ifconfig
Motivation: This use case is useful when you want to convert the output of a command to JSON for further processing or analysis. Converting the output to JSON makes it easier to manipulate and extract specific information programmatically.
Explanation:
ifconfig: This is the command whose output we want to convert to JSON.jc: This is the command we are using to perform the JSON conversion.--ifconfig: This argument tellsjcto parse the input as the output of theifconfigcommand.
Example output:
{
"interfaces": {
"eth0": {
"inet4": {
"address": "192.168.1.100",
"netmask": "255.255.255.0"
},
"inet6": {
"address": "fe80::1",
"prefix_length": "64"
}
},
"wlan0": {
"inet4": {
"address": "192.168.1.101",
"netmask": "255.255.255.0"
},
"inet6": {
"address": "fe80::2",
"prefix_length": "64"
}
}
}
}
Use Case 2: Convert command output to JSON via magic syntax
The jc command also supports a magic syntax that allows you to convert the output of a command to JSON without using a pipe. Here’s an example:
jc ifconfig
Motivation: This use case is useful when you want to quickly convert the output of a command to JSON without the need for additional piping. It provides a more concise and readable way to use jc.
Explanation:
ifconfig: This is the command whose output we want to convert to JSON. We pass it directly tojcusing the magic syntax.
Example output:
{
"interfaces": {
"eth0": {
"inet4": {
"address": "192.168.1.100",
"netmask": "255.255.255.0"
},
"inet6": {
"address": "fe80::1",
"prefix_length": "64"
}
},
"wlan0": {
"inet4": {
"address": "192.168.1.101",
"netmask": "255.255.255.0"
},
"inet6": {
"address": "fe80::2",
"prefix_length": "64"
}
}
}
}
Use Case 3: Output pretty JSON via pipe
To output the converted JSON in a pretty and human-readable format, you can use the -p flag with the jc command. Here’s an example:
ifconfig | jc --ifconfig -p
Motivation: This use case is useful when you want to easily read and understand the converted JSON output. The -p flag ensures the output is formatted with indentation and line breaks, making it easier to analyze the data visually.
Explanation:
ifconfig: This is the command whose output we want to convert to JSON.jc: This is the command we are using to perform the JSON conversion.--ifconfig: This argument tellsjcto parse the input as the output of theifconfigcommand.-p: This flag instructsjcto pretty-print the JSON output.
Example output:
{
"interfaces": {
"eth0": {
"inet4": {
"address": "192.168.1.100",
"netmask": "255.255.255.0"
},
"inet6": {
"address": "fe80::1",
"prefix_length": "64"
}
},
"wlan0": {
"inet4": {
"address": "192.168.1.101",
"netmask": "255.255.255.0"
},
"inet6": {
"address": "fe80::2",
"prefix_length": "64"
}
}
}
}
Use Case 4: Output pretty JSON via magic syntax
Similar to the previous use case, you can also use the -p flag with the magic syntax to output pretty JSON. Here’s an example:
jc -p ifconfig
Motivation: This use case is useful when you prefer using the magic syntax of jc and still want to output the JSON in a human-readable format. The -p flag ensures the readability of the JSON output.
Explanation:
ifconfig: This is the command whose output we want to convert to JSON. We pass it directly tojcusing the magic syntax.jc: This is the command we are using to perform the JSON conversion.-p: This flag instructsjcto pretty-print the JSON output.
Example output:
{
"interfaces": {
"eth0": {
"inet4": {
"address": "192.168.1.100",
"netmask": "255.255.255.0"
},
"inet6": {
"address": "fe80::1",
"prefix_length": "64"
}
},
"wlan0": {
"inet4": {
"address": "192.168.1.101",
"netmask": "255.255.255.0"
},
"inet6": {
"address": "fe80::2",
"prefix_length": "64"
}
}
}
}
Use Case 5: Convert command output with custom parser
The jc command allows you to use custom parsers to handle commands that are not supported out of the box. Custom parsers can be defined as Python modules. Here’s an example:
git log | jc custom/gitlog.py
Motivation: This use case is useful when you want to convert the output of a command that is not supported by the default jc parsers. By creating a custom parser, you can convert the output of the command to JSON, enabling further processing.
Explanation:
git log: This is the command whose output we want to convert to JSON.jc: This is the command we are using to perform the JSON conversion.custom/gitlog.py: This argument specifies the custom parser to use for the command output.
Example output (custom/gitlog.py):
[
{
"commit": "ac7a423",
"author": "Alice",
"date": "2021-01-01",
"message": "Added feature XYZ"
},
{
"commit": "b5023cf",
"author": "Bob",
"date": "2020-12-31",
"message": "Fix issue ABC"
}
]
Use Case 6: Convert command output with multiple parsers
The jc command supports using multiple parsers in a single conversion. This is useful when a command output consists of multiple sections or pieces of information. Here’s an example:
netstat -an | jc --udp --tcp
Motivation: This use case is useful when the output of a command contains different sections or categories of data that need to be converted separately. By using multiple parsers, each section can be parsed and converted to individual JSON objects.
Explanation:
netstat -an: This is the command whose output we want to convert to JSON.jc: This is the command we are using to perform the JSON conversion.--udp: This argument tellsjcto parse the input using the UDP parser.--tcp: This argument tellsjcto parse the input using the TCP parser.
Example output:
{
"udp": [
{
"local_address": "0.0.0.0:53",
"foreign_address": "0.0.0.0:*",
"state": "LISTEN"
},
{
"local_address": "192.168.1.100:12345",
"foreign_address": "192.168.1.200:80",
"state": "ESTABLISHED"
}
],
"tcp": [
{
"local_address": "0.0.0.0:22",
"foreign_address": "0.0.0.0:*",
"state": "LISTEN"
},
{
"local_address": "192.168.1.100:54321",
"foreign_address": "192.168.1.201:443",
"state": "ESTABLISHED"
}
]
}
Use Case 7: Specify custom options for parsers
The jc command allows you to specify custom options for parsers. This is useful when you want to modify the behavior of a parser to fit your specific needs. Here’s an example:
lsblk | jc --lsblk --indent 4
Motivation: This use case is useful when you want to customize the parsing options for a specific command output. By specifying custom options, you can control how the command output is parsed and converted to JSON.
Explanation:
lsblk: This is the command whose output we want to convert to JSON.jc: This is the command we are using to perform the JSON conversion.--lsblk: This argument tellsjcto parse the input as the output of thelsblkcommand.--indent 4: This option specifies the indentation level to use when pretty-printing the JSON output.
Example output:
{
"blockdevices": [
{
"name": "sda",
"maj:min": "8:0",
"rm": "0",
"size": "238.5G",
"ro": "0",
"type": "disk",
"mountpoint": null,
"children": [
{
"name": "sda1",
"maj:min": "8:1",
"rm": "0",
"size": "512M",
"ro": "0",
"type": "part",
"mountpoint": "/boot/efi"
},
{
"name": "sda2",
"maj:min": "8:2",
"rm": "0",
"size": "238G",
"ro": "0",
"type": "part",
"mountpoint": "/"
}
]
},
{
"name": "sdb",
"maj:min": "8:16",
"rm": "0",
"size": "931.5G",
"ro": "0",
"type": "disk",
"mountpoint": null
}
]
}
Use Case 8: Convert command output to JSON with Explorer-like output
The jc command provides an --explorer option which gives the converted JSON output in a convenient, hierarchical structure similar to an explorer. Here’s an example:
ls -l | jc --ls -l --explorer
Motivation: This use case is useful when you want to visualize the converted JSON output in an explorer-like format, making it easier to navigate and understand the data structure.
Explanation:
ls -l: This is the command whose output we want to convert to JSON.jc: This is the command we are using to perform the JSON conversion.--ls -l: This argument tellsjcto parse the input as the output of thels -lcommand.--explorer: This option enables the explorer-like output format.
Example output:
/
├── bin
│ ├── ls -> /usr/bin/ls
│ ├── mkdir -> /usr/bin/mkdir
│ └── touch -> /usr/bin/touch
├── usr
│ ├── bin
│ │ ├── ls
│ │ ├── mkdir
│ │ └── touch
│ └── local
│ └── bin
├── home
│ └── user
│ └── docs
│ ├── file1.txt
│ └── file2.txt
└── var
└── log
└── app.log
Conclusion
The jc command provides a convenient way to convert the output of various commands to JSON format. This article covered 8 different use cases demonstrating the versatility and power of the jc command.
By using jc, you can easily convert command output to JSON via pipe or with the magic syntax. You can also output pretty JSON for better readability and navigate explorer-like structures. Additionally, jc allows you to create and use custom parsers, specify parser options, and work with multiple parsers in a single conversion.
With these use cases and examples, you should be well-equipped to leverage jc for converting command output to JSON in your everyday tasks and automation workflows.
