title: How to convert txt to csv files in Azure Data Factory
body: <p>I'm trying to move files in between multiple gen1 Azure data lake storage instances without having to resort to writing an Azure App Function or directly calling the Azure storage SDK.</p>
  
  <p>The situation is that I've got a few text files in data lake 1 called <code>test1.txt</code> and <code>test2.txt</code>. They're both files with tabs as delimiters. When I try to use the copy activity with <code>.csv</code> as extension, the files do get moved over to data lake 2, but stay <code>.txt</code> files.</p>
  
  <p>The copy activity source and sink looks as follows:</p>
  
  <pre><code>{
      "typeProperties": {
          "source": {
              "type": "DelimitedTextSource",
              "storeSettings": {
                  "type": "AzureDataLakeStoreReadSettings",
                  "recursive": true,
                  "wildcardFileName": "*.*",
                  "enablePartitionDiscovery": false
              },
              "formatSettings": {
                  "type": "DelimitedTextReadSettings"
              }
          },
          "sink": {
              "type": "DelimitedTextSink",
              "storeSettings": {
                  "type": "AzureDataLakeStoreWriteSettings"
              },
              "formatSettings": {
                  "type": "DelimitedTextWriteSettings",
                  "quoteAllText": true,
                  "fileExtension": ".csv"
              }
          }
      }
  }
  </code></pre>
  
  <p>I've tried copying to a blob container as well, but the same issue remains: the files keep their <code>.txt</code> extension.</p>
  
  <p>Is it possible to change the file extension after a copy?</p>