How to Check Aria2 Download Link Without Downloading?

To verify the validity and details of a download link in aria2 without actually fetching the full file, you can use the --dry-run parameter. This command allows aria2 to connect to the server, validate the URL, and check file availability or size while skipping the actual data download. It is an efficient way to test URLs and troubleshoot scripts before committing time and bandwidth to a complete transfer.

When managing automated scripts or handling large batches of downloads, verifying that your source links are active and correct is crucial. The aria2c command-line tool provides a built-in mechanism exactly for this purpose.

The --dry-run Command

By appending --dry-run to your execution string, aria2 performs all the initial handshakes and requests required to start a download, but it terminates the process immediately before writing the file to your disk.

aria2c --dry-run "https://example.com/file.zip"

What Happens During a Dry Run?

When you execute this command, aria2 goes through the following steps:

  • DNS Resolution: Resolves the domain name of the host server.
  • Server Connection: Establishes a connection to the remote server.
  • HTTP/FTP Handshake: Sends the initial request headers to the server.
  • Link Validation: Checks if the file exists (returning a 200 OK status or an error like 404 Not Found).
  • Metadata Retrieval: If successful, it prints out file information, such as the total file size and content type, before safely disconnecting.