yq:tldr:f0110

yq: Output the first element in a YAML file that contains only an array (v4+).

$ yq eval '.[0]' ${filename-yaml}

try on your machine

This command is using a tool called yq to evaluate and manipulate YAML files. Here's a breakdown of the command structure:

yq: This is the command to run the yq tool.
eval: This is the command within yq to evaluate or manipulate YAML.
'.[0]': This is the YAML expression that will be evaluated. In this case, it's using a JSONPath-like syntax to select the first element in the YAML document. The . represents the root of the YAML document, and [0] selects the first element.
${filename-yaml}: This is a shell variable that is being used to specify the filename or path to the YAML file you want to evaluate. ${filename-yaml} is a shorthand way of specifying a default value for the filename variable if it is not set in the environment. If the filename variable is not set, it will default to the value yaml.

So, the overall purpose of this command is to evaluate the specified YAML file and extract the first element from it using the yq tool.

This explanation was created by an AI. In most cases those are correct. But please always be careful and never run a command you are not sure if it is safe.

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