Rotate PDF file with PyPDF2

rotatepdf.py

#!/usr/bin/env python3

import PyPDF2

pdfIn = open('original.pdf', 'rb') # exchange the 'original.pdf' with a name of your file 
pdfReader = PyPDF2.PdfFileReader(pdfIn)
pdfWriter = PyPDF2.PdfFileWriter()

for pageNum in range(pdfReader.numPages):
    page = pdfReader.getPage(pageNum)
    page.rotateClockwise(90)
    pdfWriter.addPage(page)

pdfOut = open('rotated.pdf', 'wb')
pdfWriter.write(pdfOut)
pdfOut.close()
pdfIn.close()

@jb0hn Really helpful!!
Some of the code written above are deprecated functions since PyPDF2 version 3.0.0.
Here is the same code but adapted:

fname = 'original.pdf' # exchange the 'original.pdf' with a name of your file
new_fname = fname.replace('.pdf', '_rotated.pdf')
pdfIn = open(fname, 'rb')
pdfReader = PyPDF2.PdfReader(pdfIn)
pdfWriter = PyPDF2.PdfWriter()

for page in pdfReader.pages:
    page.rotate(90)
    pdfWriter.add_page(page)

pdfOut = open(new_fname, 'wb')
pdfWriter.write(pdfOut)
pdfOut.close()
pdfIn.close()