Convert input.pdf to output.txt. Note the -i to attach stdin and stdout.
docker run --rm -i arjobsen/pdftotext < input.pdf > output.txt
Convert input.pdf and print to stdout.
docker run --rm -i arjobsen/pdftotext < input.pdf
Execute with options. E.g. convert only the first page.
docker run --rm -i arjobsen/pdftotext -l 1 < input.pdf
See command help and version
docker run --rm arjobsen/pdftotext -h