How to Load a Saved Session File in aria2?

When using the aria2 command-line download utility, you can resume and recover your previous download progress by loading a saved session file upon startup. This article explains the exact command-line flag required to import a session file, how to automatically save your sessions to prevent data loss, and provides practical examples for integrating these commands into your daily workflow.

The Core Flag: --input-file

To tell aria2 to load a previously saved session file when it starts up, you use the --input-file flag (or its short form, -i).

When you pass a file to this flag, aria2 reads the list of URIs and download configurations stored within that file and adds them back into the download queue.

aria2c --input-file=session.txt

(Alternatively, you can use aria2c -i session.txt)

Setting Up a Complete Session Workflow

Simply loading a session file isn’t enough; you also need to make sure aria2 is actively saving your current progress to that same file. To create a seamless “save and resume” loop, you should combine the loading flag with the saving flag.

1. Saving the Session (--save-session)

The --save-session flag specifies where aria2 should output your current download progress. If aria2 is interrupted, it will write all unfinished downloads to this file.

2. The Ideal Command Combination

To ensure that aria2 both loads your past downloads and updates them as they progress, run the command with both flags pointing to the same file path:

aria2c --input-file=session.txt --save-session=session.txt

Important Note: Before running this command for the very first time, the file (e.g., session.txt) must actually exist on your system, even if it is completely blank. If the file does not exist, aria2 will throw an error and refuse to start. You can create an empty file quickly using the touch session.txt command on Linux/macOS or type nul > session.txt on Windows.

Automating the Process via Configuration File

If you don’t want to type these flags every time you launch the application, you can add them to your permanent aria2 configuration file (typically located at ~/.aria2/aria2.conf).

Add the following lines to your configuration file:

input-file=/path/to/your/session.txt
save-session=/path/to/your/session.txt
save-session-interval=60

The save-session-interval=60 option is a highly recommended addition. By default, aria2 only saves the session file when the program exits cleanly. Adding the interval flag forces aria2 to back up your download state to the session file every 60 seconds, protecting your progress even in the event of a sudden power outage or system crash.