How to diagnose this, fails on 3.6.3, works on 3.5.2?

[Chris Green]

I have a fairly simple little python program to automate starting an
editor on a wiki page.  It works fine on the system where I wrote it
(xubuntu 16.04, python 3 version 3.5.2) but it comes up with the
following error on a newer system (xubuntu 17.10, python 3 version
3.6.3).

Here is the error:-

    chris$ no
    Traceback (most recent call last):
      File "/home/chris/bin/no", line 59, in <module>
        os.execvp("vi", ("", monthFile,))
      File "/usr/lib/python3.6/os.py", line 559, in execvp
        _execvpe(file, args)
      File "/usr/lib/python3.6/os.py", line 594, in _execvpe
        exec_func(fullname, *argrest)
    ValueError: execv() arg 2 first element cannot be empty

Has execvp() become stricter in 3.6.3 or what?


... and here is the program:-


    #!/usr/bin/python3
    #
    #
    # Create Dokuwiki journal month pages
    #
    import sys
    import os
    import time
    import calendar

    jdir = "/home/chris/wiki/data/pages/journal"
    #
    #
    # Default month and year is 'now'
    #
    month = time.localtime().tm_mon
    year = time.localtime().tm_year
    #
    #
    # If one parameter is given then it's the month
    #
    if len(sys.argv) == 2:
        month = int(sys.argv[1])
    #
    #
    # If two parameters are given they are month and year
    #
    if len(sys.argv) == 3:
        year = int(sys.argv[2])
        month = int(sys.argv[1])
    #
    #
    #
    #
    #
    #
    # Check if the year directory exists and create it if it doesn't
    #
    yearDir = os.path.join(jdir, str(year))
    if not os.path.exists(yearDir):
        os.mkdir(yearDir)
    #
    #
    # Check if month file exists, create it if it doesn't and write heading and links
    #
    if month < 10:
        monthFile = os.path.join(yearDir, '0' + str(month) + '.txt')
    else:
        monthFile = os.path.join(yearDir, str(month) + '.txt')
    if not os.path.exists(monthFile):
        monthName = calendar.month_name[month]
        f = open(monthFile, 'w')
        f.write(monthName + " " + str(year) + "\n")
        for i in range(len(monthName) + 5):
            f.write("=")
        f.write("\n")
        f.close()

    os.execvp("vi", ("", monthFile,))

-- 
Chris Green
·