Python Script: PDF Extract

While playing around with a couple of other scripts, I got this idea that I wanted to incorporate extracting data from PDFs.  Nothing fancy here, just a recursive search for PDFs, we're extracting the text, and we're writing it out to a text file:  output.txt

#!/usr/bin/python3
import glob
import PyPDF2
folder_path = './'
for filename in glob.iglob(folder_path + '**/*.pdf', recursive=True):
    file = open(filename, 'rb')
    pdfReader = PyPDF2.PdfFileReader(file, strict=False)
    pageObj = pdfReader.getPage(0)
    f1=open('./output.txt', 'a+')
    f1.write(pageObj.extractText())
    f1.close()