Both the solutions below are designed NOT to launch the print dialog. These solutions will either print the active webpage to your local printer or to a PDF file without having to deal with the dialog.

UPDATED POST 08-19-2021

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I wanted to save the output to PDF vs printing to paper. I was shocked how hard it was to print to a PDF using the geckodriver and selenium. With the ‘chromedriver’ you can call the function ‘execute_cdp_cmd’ and pass Page.printToPDF. The geckodriver doesn’t have ‘execute_cdp_cmd’.

When I looked through Stack Overflow for inspiration, I discover multiple open question on printing pdf using the geckodriver with selenium. After seeing that this was a problem, I looked through the issues in selenium and the bug reports for mozilla. Again this was a problem that others had.

Some of the bug reports mentioned that certain switches used in the print process no longer worked.

profile.set_preference("print.print_to_file", True)
profile.set_preference("print.print_to_filename", "/tmp/file.pdf")

I decided to look at the source code for mozilla gecko-dev for a potential solution. After hours of research I found that the switches above were replaced with new ones and that another printer variable had also been replaced. After some testing, I was able to get your webpage to save as PDF.

The code below will print a webpage to a PDF with all the links enabled. I would recommend adding some error handling to the code. One part of the code that I need to improve on the filename part. You should be able to add a function that will rename the file, which would allow you to print as many files as you want in a single session.

from time import sleep
from selenium import webdriver
from selenium.webdriver.common.keys import Keys
from selenium.webdriver.firefox.options import Options
from selenium.webdriver.firefox.options import FirefoxProfile

firefox_options = Options()
firefox_options.add_argument("--disable-infobars")
firefox_options.add_argument("--disable-extensions")
firefox_options.add_argument("--disable-popup-blocking")

profile_options = FirefoxProfile()
user_agent = 'Mozilla/5.0 (Macintosh; Intel Mac OS X 11.5; rv:90.0) Gecko/20100101 Firefox/90.0'
profile_options.set_preference('profile_options = FirefoxProfile()', user_agent)
profile_options.set_preference("print_printer", "Mozilla Save to PDF")
profile_options.set_preference("print.always_print_silent", True)
profile_options.set_preference("print.show_print_progress", False)
profile_options.set_preference('print.save_as_pdf.links.enabled', True)
profile_options.set_preference("print.printer_Mozilla_Save_to_PDF.print_to_file", True)

# set your own file path
profile_options.set_preference('print.printer_Mozilla_Save_to_PDF.print_to_filename',
                               "tmp/testprint.pdf")


driver = webdriver.Firefox(executable_path='/usr/local/bin/geckodriver', options=firefox_options,
                           firefox_profile=profile_options)


URL = 'https://finance.yahoo.com/'


driver.get(URL)

sleep(10)

search_field_id = 'yfin-usr-qry'

element_search_field = driver.find_element_by_id(search_field_id)
element_search_field.clear()
element_search_field.send_keys('TSLA')
element_search_field.send_keys(Keys.ENTER)

sleep(10)

driver.execute_script("window.print()")

sleep(20)

driver.quit()

ORIGINAL POST 08-18-2021

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I decided to look at your issue, because I’m interested in selenium functionality.

I looked through the source code of the geckodriver and found printUtils.js, which provides details on the switches used in the print process, such as these:

firefox_options.set_preference("print.always_print_silent", True)
firefox_options.set_preference("print.show_print_progress", False)

After removing some of your code and adding some, I was able to print to my HP printer with the code below without dealing with a print dialog box:

from time import sleep
from selenium import webdriver
from selenium.webdriver.common.keys import Keys
from selenium.webdriver.firefox.options import Options
from selenium.webdriver.firefox.options import FirefoxProfile

firefox_options = Options()
firefox_options.add_argument("--disable-infobars")
firefox_options.add_argument("--disable-extensions")
firefox_options.add_argument("--disable-popup-blocking")

profile_options = FirefoxProfile()
user_agent = 'Mozilla/5.0 (Macintosh; Intel Mac OS X 11.5; rv:90.0) Gecko/20100101 Firefox/90.0'
firefox_options.set_preference('profile_options = FirefoxProfile()', user_agent)
firefox_options.set_preference("print.always_print_silent", True)
firefox_options.set_preference("print.show_print_progress", False)
firefox_options.set_preference("pdfjs.disabled", True)

driver = webdriver.Firefox(executable_path='/usr/local/bin/geckodriver', options=firefox_options)

URL = 'https://finance.yahoo.com/'

driver.get(URL)

sleep(10)

search_field_id = 'yfin-usr-qry'

element_search_field = driver.find_element_by_id(search_field_id)
element_search_field.clear()
element_search_field.send_keys('TSLA')
element_search_field.send_keys(Keys.ENTER)

sleep(10)
driver.execute_script("window.print()")

----------------------------------------
My system information
----------------------------------------
Platform:    Apple
OS:          10.15.7
Python:      3.9
Selenium:    3.141
Firefox:     90.0.2
Geckodriver: 0.29.0

----------------------------------------