system · Command reference

`qzx inspectPort`

What it does

Checks whether a local port is bound and reports the owning process without terminating it

Command maturity: Alpha

Available for real use and feedback while its interface and behavior can still evolve. This is the current development-checkout assessment. Every future immutable release tag preserves the exact assessment shipped by that version. Available in PyPI 0.2.2.0.15. This page documents the 0.2.2.0.15 alpha development checkout.

Behavior and built-in protections

Inspects without changing state

Direct execution for this operation

Uses a native tool when needed

Works without network access

Uses your current permissions; results can vary

inspectPort is strictly read-only and never changes process state.

This safety classification was reviewed by Claude Opus 5.5 (Anthropic) against implementation digest sha256:1d5d6e4843aec55d11027a9630f683cf24297a269475e95b6963cbe99bc8e6be on 2026-10-08.

Exact syntax

qzx inspectPort <port> --json

Parameters

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Name	Type	Required	Default	Description
port	int	Yes	Not declared	Port number to inspect

Input examples

qzx inspectPort 3000

Inspect the listener and obtain its PID and creation time

qzx inspectPort 5432 --json

Return the complete structured inspection result

For the complete structured payload, add --json: qzx inspectPort <port> --json

Representative output example

This illustrative JSON is derived from the current implementation-backed result contract. It shows what the command can return without claiming a recorded execution; values vary with inputs, host, permissions, and optional tools.

Example command: qzx inspectPort 3000 --json

{
    "success": true,
    "message": "Checks whether a local port is bound and reports the owning process without terminating it. In this illustrative example, the command completed successfully.",
    "meta": {
        "command": "inspectPort",
        "command_maturity": {
            "stage": "alpha",
            "label": "Alpha",
            "sequence": 2,
            "public_executable": true,
            "stability": "interface_may_change",
            "summary": "Available for real use and feedback while its interface and behavior can still evolve.",
            "promotion_review_required": false,
            "assessment_scope": "development_checkout"
        },
        "duration_ms": 0,
        "schema_version": 1
    },
    "errors": [],
    "in_use": true,
    "limitations": [
        "Example value"
    ],
    "observed_pids": [
        3
    ],
    "port": 3,
    "processes": [
        {
            "pid": 4210,
            "name": "python",
            "cpu_percent": 4.2,
            "memory_readable": "82.4 MiB"
        }
    ],
    "status": "free"
}

View the JSON result contract

{
    "type": "object",
    "properties": {
        "success": {
            "type": "boolean"
        },
        "message": {
            "type": "string"
        },
        "error": {
            "type": "string"
        },
        "error_code": {
            "type": "string"
        },
        "status": {
            "type": "string",
            "enum": [
                "free",
                "in_use"
            ]
        },
        "port": {
            "type": "integer",
            "minimum": 1,
            "maximum": 65535
        },
        "in_use": {
            "type": [
                "boolean",
                "null"
            ]
        },
        "observed_pids": {
            "type": "array",
            "items": {
                "type": "integer"
            }
        },
        "processes": {
            "type": "array",
            "items": {
                "type": "object",
                "additionalProperties": true
            }
        },
        "limitations": {
            "type": "array",
            "items": {
                "type": "string"
            }
        },
        "errors": {
            "type": "array",
            "items": {
                "type": "string"
            }
        },
        "meta": {
            "type": "object",
            "required": [
                "command",
                "command_maturity",
                "duration_ms",
                "schema_version"
            ],
            "properties": {
                "command": {
                    "type": "string"
                },
                "command_maturity": {
                    "type": "object",
                    "required": [
                        "stage",
                        "label",
                        "sequence",
                        "public_executable",
                        "stability",
                        "summary",
                        "promotion_review_required",
                        "assessment_scope"
                    ],
                    "properties": {
                        "stage": {
                            "type": "string"
                        },
                        "label": {
                            "type": "string"
                        },
                        "sequence": {
                            "type": "integer"
                        },
                        "public_executable": {
                            "type": "boolean"
                        },
                        "stability": {
                            "type": "string"
                        },
                        "summary": {
                            "type": "string"
                        },
                        "promotion_review_required": {
                            "type": "boolean"
                        },
                        "assessment_scope": {
                            "type": "string"
                        },
                        "note": {
                            "type": "string"
                        },
                        "review": {
                            "type": "object",
                            "required": [
                                "reviewed_on",
                                "rationale",
                                "evidence"
                            ],
                            "properties": {
                                "reviewed_on": {
                                    "type": "string",
                                    "format": "date"
                                },
                                "rationale": {
                                    "type": "string"
                                },
                                "evidence": {
                                    "type": "array",
                                    "minItems": 1,
                                    "items": {
                                        "type": "string"
                                    }
                                },
                                "replacement": {
                                    "type": "string"
                                }
                            },
                            "additionalProperties": false
                        }
                    },
                    "additionalProperties": true
                },
                "duration_ms": {
                    "type": "number"
                },
                "schema_version": {
                    "type": "integer"
                }
            },
            "additionalProperties": true
        }
    },
    "additionalProperties": true,
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "required": [
        "message",
        "meta",
        "success"
    ]
}

Errors and limits

The public contract requires success=false and a descriptive message on failure. This catalog does not yet declare a command-specific error taxonomy; inspect the result and do not invent error codes.

QZX is alpha software. Optional dependencies, permissions, and host capabilities can change the result.

Evidence workflow: requires a controlled privileged environment.

Evidence and provenance

Implementation: src/qzx/commands/system/inspect_port.py
Tests: tests/test_system_commands/test_inspect_port.py
Documentation channel: Development documentation 0.2.2.0.15 · main · sha256:b91acee86268edb7cb018a94e089ff8e95835eda3f2cf08b39796c0ab9654693
Availability: 0.2.2.0.15 or earlier

Practical guide

Learn when qzx inspectPort fits the task, how native operating-system tools compare, and which details matter in automation.

9 min read
How to find what is using a port on Windows, Linux, and macOS
When a server says a port is already in use, identify the listener before changing process state. Compare native tools with one structured QZX diagnostic.
Read the practical guide

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