yq/pkg/yqlib/doc/operators/headers/system-operators.md

System Operators

The system operator allows you to run an external command and use its output as a value in your expression.

Security warning: The system operator is disabled by default. You must explicitly pass --enable-system-operator to use it.

Usage

yq --enable-system-operator --null-input '.field = system("command"; "arg1")'

The operator takes:

• A command string (required)
• An argument or array of arguments separated by ; (optional)

The current matched node's value is serialised and piped to the command via stdin. The command's stdout (with trailing newline stripped) is returned as a string.

Disabling the system operator

The system operator is disabled by default. When disabled, a warning is logged and null is returned instead of running the command.

Use --enable-system-operator flag to enable it.