jq:tldr:a69c2

This command performs the following actions:

1. ${cat filename-json}: This is a parameter expansion that represents a command substitution. It executes the cat command with the argument filename-json. cat is a command used to concatenate and display the contents of files. So, it reads the contents of the file named filename-json.

2. |: This is the pipe symbol, used to redirect the output of the previous command to the input of the next command.

3. jq: It is a lightweight command-line JSON processor. It allows you to parse and manipulate JSON data.

4. '. ${select} ${{"key1": "value1", "key2": "value2", ---}}': This is the argument provided to the jq command. It is a filter expression that specifies how the JSON data should be processed.

Within the filter expression:

• ${select} is a placeholder that is expected to be replaced with a specific value.
• {{"key1": "value1", "key2": "value2", ---}} represents a JSON object (in key-value format) enclosed within curly braces. The specific keys and values are not mentioned.

So, when executed, this command reads the content of the file filename-json, passes it to jq, and applies the specified filter expression to process the JSON data. The ${select} placeholder is expected to be replaced with a specific value, and the JSON object is used within the filter expression for the desired processing.