What is a free software for batch processing PDF via command line?

Good afternoon, need free FOR allows batch processing a large number of PDF files
Namely, there is a network folder where scanned various documents, letters, etc.
But everyone has their own scan settings, and it turns out someone may be in color to scan, who in very good quality, with the result that file a large number of megabytes begins to weigh, etc. etc.

Need such which could be called from bat file, and it would peragallo files under exposed settings, such as all in grayscale, 300 dpi, such that the compression quality
June 10th 19 at 16:30
1 answer
June 10th 19 at 16:32
Thank you, I read, just did not understand which parameters are responsible for handling the quality
toli --toli --compress linearize (strange description of them) - providenci_Dare commented on June 10th 19 at 16:35

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