# Running Sling

The `sling run` command is the primary mechanism for executing data movement operations in Sling CLI. It provides a flexible interface for transferring data between various sources and targets, with support for different replication modes and configuration options.

There are 2 primary ways to configure and run sling, using:

* [**CLI Flags**](#cli-flags-overview): quick ad-hoc runs from your terminal shell or script.
* [**Replication**](https://docs.slingdata.io/concepts/replication): streams defined in a YAML or JSON file.

***

Furthermore, you'll find plenty of examples on how to use Sling:

* [Database to Database](https://github.com/slingdata-io/sling-docs/blob/master/sling-cli/run/examples/database-to-database.md)
* [Database to File](https://github.com/slingdata-io/sling-docs/blob/master/sling-cli/run/examples/database-to-file.md)
* [File to Database](https://github.com/slingdata-io/sling-docs/blob/master/sling-cli/run/examples/file-to-database.md)

## CLI Flags Overview

For quickly running ad-hoc operations from the terminal, using CLI flags is often best. Here are some examples using:

{% code overflow="wrap" %}

```bash
# Load all tables in a schema in with 3 threads
$ export SLING_THREADS=3
$ sling run \
    --src-conn MY_SOURCE_DB \
    --src-stream 'source_schema.*' \
    --tgt-conn MY_TARGET_DB \
    --tgt-object 'target_schema.{stream_table}'
    --mode full-refresh
    
# Pipe in your json file and flatten the nested keys into their own columns
$ cat /tmp/my_file.json | sling run --src-options '{"flatten": "true"}' --tgt-conn MY_TARGET_DB --tgt-object 'target_schema.target_table' --mode full-refresh

# Read folder containing many CSV files
$ sling run \
    --src-stream 'file:///tmp/my_csv_folder/' \
    --tgt-conn MY_TARGET_DB --tgt-object 'target_schema.target_table' \
    --mode full-refresh

# Load only latest data from one source DB to another.
$ sling run \
    --src-conn MY_SOURCE_DB \
    --src-stream 'source_schema.source_table' \
    --tgt-conn MY_TARGET_DB \
    --tgt-object 'target_schema.target_table' \
    --mode incremental \
    --primary-key 'id' --update-key 'last_modified_dt' 

# Export / Backup database tables to JSON files
$ sling run \
    --src-conn MY_SOURCE_DB \
    --src-stream 'source_schema.source_table' \
    --tgt-conn MY_S3_BUCKET \
    --tgt-object 's3://my-bucket/my_json_folder/' \
    --tgt-options '{"file_max_rows": 100000, "format": "jsonlines"}'
```

{% endcode %}

## Interface Specifications

<table data-full-width="false"><thead><tr><th width="215.4264102691841">CLI Flag</th><th>Description</th></tr></thead><tbody><tr><td><code>--src-conn</code></td><td>The source database connection (name, conn string or URL).</td></tr><tr><td><code>--tgt-conn</code></td><td>The target database connection (name, conn string or URL).</td></tr><tr><td><code>--src-stream</code></td><td>The source table (schema.table), local / cloud file path. Can also be the path of sql file or in-line text to use as query. Use <code>file://</code> for local paths.</td></tr><tr><td><code>--tgt-object</code></td><td>The target table (schema.table) or local / cloud file path. Use <code>file://</code> for local paths. See <a href="../concepts/replication/runtime-variables">here</a> for details on runtime variables.</td></tr><tr><td><code>--mode</code></td><td>The target load <a href="../concepts/replication/modes">mode</a> to use: <code>incremental</code>, <code>truncate</code>, <code>full-refresh</code>, <code>backfill</code> or <code>snapshot</code>. Default is <code>full-refresh</code>.</td></tr><tr><td><code>--primary-key</code></td><td>The column(s) to use as primary key (for <code>incremental</code> mode). If composite key, use a comma-delimited string.</td></tr><tr><td><code>--update-key</code></td><td>The column to use as update key (for <code>incremental</code> mode).</td></tr><tr><td><code>--src-options</code></td><td>In-line options to further configure source (JSON or YAML). See <a href="../concepts/replication/source-options">here</a> for details.</td></tr><tr><td><code>--tgt-options</code></td><td>In-line options to further configure target (JSON or YAML). See <a href="../concepts/replication/target-options">here</a> for details.</td></tr><tr><td><code>--stdout</code></td><td>Output the stream to standard output (STDOUT).</td></tr><tr><td><code>--select</code></td><td>Select or exclude specific columns from the source stream. (comma separated). Use <code>-</code> prefix to exclude.</td></tr><tr><td><code>--transforms</code></td><td>An object/map, or array/list of built-in transforms to apply to records (JSON or YAML).</td></tr><tr><td><code>--columns</code></td><td>An object/map to specify the type that a column should be cast as (JSON or YAML).</td></tr><tr><td><code>--streams</code></td><td>Only run specific streams from a replication (comma separated). See <a href="../concepts/replication/tags-wildcards">here</a> for details.</td></tr></tbody></table>

## Features

* **Flexible Data Sources**: Supports databases, files, cloud storage, and standard input
* **Multiple Load Modes**: Includes full refresh, incremental, snapshot, and truncate modes
* **Data Transformations**: Allows column selection, type casting, and custom transformations
* **Progress Tracking**: Monitors row counts, bytes transferred, and constraint violations
* **Error Handling**: Provides detailed error reporting and validation

The `sling run` command is designed to be both powerful and flexible, accommodating various data movement scenarios while maintaining ease of use through consistent parameter patterns and comprehensive documentation.