mupdf/docs/tools/mutool-merge.rst
The merge command is used to pick out pages from two or more files and merge them into a new output file.
.. code-block:: bash
mutool merge [-o output.pdf] [-O options] input1.pdf [pages1] [input2.pdf] [pages2] ...
[-o output.pdf]
The output filename. Defaults to "out.pdf" if not supplied.
[-O options]
See :doc:/reference/common/pdf-write-options.
input1.pdf
The first document.
[pages1]
Comma separated list of page ranges for the first document (input.pdf). The first page is "1", and the last page is "N". The default is "1-N".
[input2.pdf]
The second document.
[pages2]
Comma separated list of page ranges for the second document (input2.pdf). The first page is "1", and the last page is "N". The default is "1-N".
...
Indicates that we add as many additional [input] & [pages] pairs as required to merge multiple documents.