Batch-convert documents to another format without opening a UI using LibreOffice headless --convert-to

Steps

1. Launch LibreOffice in headless mode so it runs without a user interface: `soffice --headless --convert-to pdf myfile.docx`
2. Convert a whole directory of files at once with a glob, e.g. `soffice --headless --convert-to pdf *.doc`
3. Route output files to a specific directory instead of the current one with `--outdir`, e.g. `soffice --headless --convert-to pdf:writer_pdf_Export --outdir /home/user *.doc`
4. Pin the exact export filter when the default guess for a target extension isn't the one you want, using the `OutputFileExtension[:OutputFilterName[:OutputFilterParams]]` syntax (e.g. `pdf:writer_pdf_Export`)
5. Point each concurrent/automated invocation at its own profile directory with `-env:UserInstallation=file:///tmp/some-unique-path` so parallel or scripted runs don't collide on the default user profile
6. Add `--nolockcheck` only if you intentionally run multiple soffice processes against shared state and understand the tradeoff — it disables the check for remote instances using the installation