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# Semantic conventions for CLI (command line interface) programs

**Status**: [Development][DocumentStatus]

This document defines semantic conventions to apply when instrumenting CLI programs, both as a caller and as callee. This document is intended for short-lived programs that end their execution, i.e. not daemon or long running background tasks.

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## Execution (callee) spans

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**Status:** ![Development](https://img.shields.io/badge/-development-blue)

This span describes CLI (Command Line Interfaces) program execution from a callee perspective.

**Span name** SHOULD be set to {process.executable.name}.
Instrumentations that have additional context about executed commands MAY use
a different low-cardinality span name format and SHOULD document it.

**Span status** SHOULD be set to Error if {process.exit.code} is not 0. Refer to
the [Recording Errors](/docs/general/recording-errors.md) document for details on how to record span status.

**Span kind** SHOULD be `INTERNAL`.

| Attribute  | Type | Description  | Examples  | [Requirement Level](https://opentelemetry.io/docs/specs/semconv/general/attribute-requirement-level/) | Stability |
|---|---|---|---|---|---|
| [`process.executable.name`](/docs/attributes-registry/process.md) | string | The name of the process executable. On Linux based systems, this SHOULD be set to the base name of the target of `/proc/[pid]/exe`. On Windows, this SHOULD be set to the base name of `GetProcessImageFileNameW`. | `otelcol` | `Required` | ![Development](https://img.shields.io/badge/-development-blue) |
| [`process.exit.code`](/docs/attributes-registry/process.md) | int | The exit code of the process. | `127` | `Required` | ![Development](https://img.shields.io/badge/-development-blue) |
| [`process.pid`](/docs/attributes-registry/process.md) | int | Process identifier (PID). | `1234` | `Required` | ![Development](https://img.shields.io/badge/-development-blue) |
| [`error.type`](/docs/attributes-registry/error.md) | string | Describes a class of error the operation ended with. [1] | `timeout`; `java.net.UnknownHostException`; `server_certificate_invalid`; `500` | `Conditionally Required` if and only if process.exit.code is not 0 | ![Stable](https://img.shields.io/badge/-stable-lightgreen) |
| [`process.command_args`](/docs/attributes-registry/process.md) | string[] | All the command arguments (including the command/executable itself) as received by the process. On Linux-based systems (and some other Unixoid systems supporting procfs), can be set according to the list of null-delimited strings extracted from `proc/[pid]/cmdline`. For libc-based executables, this would be the full argv vector passed to `main`. | `["cmd/otecol", "--config=config.yaml"]` | `Recommended` | ![Development](https://img.shields.io/badge/-development-blue) |
| [`process.executable.path`](/docs/attributes-registry/process.md) | string | The full path to the process executable. On Linux based systems, can be set to the target of `proc/[pid]/exe`. On Windows, can be set to the result of `GetProcessImageFileNameW`. | `/usr/bin/cmd/otelcol` | `Recommended` | ![Development](https://img.shields.io/badge/-development-blue) |

**[1] `error.type`:** The `error.type` SHOULD be predictable, and SHOULD have low cardinality.

When `error.type` is set to a type (e.g., an exception type), its
canonical class name identifying the type within the artifact SHOULD be used.

Instrumentations SHOULD document the list of errors they report.

The cardinality of `error.type` within one instrumentation library SHOULD be low.
Telemetry consumers that aggregate data from multiple instrumentation libraries and applications
should be prepared for `error.type` to have high cardinality at query time when no
additional filters are applied.

If the operation has completed successfully, instrumentations SHOULD NOT set `error.type`.

If a specific domain defines its own set of error identifiers (such as HTTP or gRPC status codes),
it's RECOMMENDED to:

- Use a domain-specific attribute
- Set `error.type` to capture all errors, regardless of whether they are defined within the domain-specific set or not.

---

`error.type` has the following list of well-known values. If one of them applies, then the respective value MUST be used; otherwise, a custom value MAY be used.

| Value  | Description | Stability |
|---|---|---|
| `_OTHER` | A fallback error value to be used when the instrumentation doesn't define a custom value. | ![Stable](https://img.shields.io/badge/-stable-lightgreen) |

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## Client (caller) spans

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**Status:** ![Development](https://img.shields.io/badge/-development-blue)

This span describes CLI (Command Line Interfaces) program execution from a caller perspective.

**Span name** SHOULD be set to {process.executable.name}.
Instrumentations that have additional context about executed commands MAY use
a different low-cardinality span name format and SHOULD document it.

**Span status** SHOULD be set to Error if {process.exit.code} is not 0. Refer to
the [Recording Errors](/docs/general/recording-errors.md) document for details on how to record span status.

**Span kind** SHOULD be `CLIENT`.

| Attribute  | Type | Description  | Examples  | [Requirement Level](https://opentelemetry.io/docs/specs/semconv/general/attribute-requirement-level/) | Stability |
|---|---|---|---|---|---|
| [`process.executable.name`](/docs/attributes-registry/process.md) | string | The name of the process executable. On Linux based systems, this SHOULD be set to the base name of the target of `/proc/[pid]/exe`. On Windows, this SHOULD be set to the base name of `GetProcessImageFileNameW`. | `otelcol` | `Required` | ![Development](https://img.shields.io/badge/-development-blue) |
| [`process.exit.code`](/docs/attributes-registry/process.md) | int | The exit code of the process. | `127` | `Required` | ![Development](https://img.shields.io/badge/-development-blue) |
| [`process.pid`](/docs/attributes-registry/process.md) | int | Process identifier (PID). | `1234` | `Required` | ![Development](https://img.shields.io/badge/-development-blue) |
| [`error.type`](/docs/attributes-registry/error.md) | string | Describes a class of error the operation ended with. [1] | `timeout`; `java.net.UnknownHostException`; `server_certificate_invalid`; `500` | `Conditionally Required` if and only if process.exit.code is not 0 | ![Stable](https://img.shields.io/badge/-stable-lightgreen) |
| [`process.command_args`](/docs/attributes-registry/process.md) | string[] | All the command arguments (including the command/executable itself) as received by the process. On Linux-based systems (and some other Unixoid systems supporting procfs), can be set according to the list of null-delimited strings extracted from `proc/[pid]/cmdline`. For libc-based executables, this would be the full argv vector passed to `main`. | `["cmd/otecol", "--config=config.yaml"]` | `Recommended` | ![Development](https://img.shields.io/badge/-development-blue) |
| [`process.executable.path`](/docs/attributes-registry/process.md) | string | The full path to the process executable. On Linux based systems, can be set to the target of `proc/[pid]/exe`. On Windows, can be set to the result of `GetProcessImageFileNameW`. | `/usr/bin/cmd/otelcol` | `Recommended` | ![Development](https://img.shields.io/badge/-development-blue) |

**[1] `error.type`:** The `error.type` SHOULD be predictable, and SHOULD have low cardinality.

When `error.type` is set to a type (e.g., an exception type), its
canonical class name identifying the type within the artifact SHOULD be used.

Instrumentations SHOULD document the list of errors they report.

The cardinality of `error.type` within one instrumentation library SHOULD be low.
Telemetry consumers that aggregate data from multiple instrumentation libraries and applications
should be prepared for `error.type` to have high cardinality at query time when no
additional filters are applied.

If the operation has completed successfully, instrumentations SHOULD NOT set `error.type`.

If a specific domain defines its own set of error identifiers (such as HTTP or gRPC status codes),
it's RECOMMENDED to:

- Use a domain-specific attribute
- Set `error.type` to capture all errors, regardless of whether they are defined within the domain-specific set or not.

---

`error.type` has the following list of well-known values. If one of them applies, then the respective value MUST be used; otherwise, a custom value MAY be used.

| Value  | Description | Stability |
|---|---|---|
| `_OTHER` | A fallback error value to be used when the instrumentation doesn't define a custom value. | ![Stable](https://img.shields.io/badge/-stable-lightgreen) |

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[DocumentStatus]: https://opentelemetry.io/docs/specs/otel/document-status
