does s4cmd accept input from stdout?

Hi

I tried something similar, but not seem working, example

echo "my file"| s4cmd put - s3://mybucket/s4cmd-test/testfile.txt &

it still expects proper source target in this case.

Start by tracing the s4cmd put command's argument parsing and source handling for the documented example `echo "my file" | s4cmd put - s3://mybucket/s4cmd-test/testfile.txt`. Check how the CLI treats `-` and identify the existing command tests; done means stdin input is accepted and uploaded to the specified S3 target without requiring a source path.

Written by the indexing model from the issue text.