Question

I like to give my user’s an example in my __doc__ usage string. Here are the important parts of the code relating to my question.

# jmetadata.py
'''
usage:     jmetadata.py inDirPath outFilePath
example:   jmetadata.py "\\\\Hal\\hal free agent 1\\backups\\videos\\" out.txt
'''

<...deleted code...>

def forPyWinTests():
    jmetadata("\\\\Hal\\hal free agent 1\\backups\\videos\\", "out.txt")

NUM_ARGS = 2
def main():
    args = sys.argv[1:]
    print args
    if len(args) != NUM_ARGS or "-h" in args or "--help" in args:
        print __doc__
        sys.exit(2)
    jmetadata(args[0], args[1])

if __name__ == '__main__':
    main()
    # print()
    # forPyWinTests()

I EXPECT this behaviour:

>jmetadata.py
[]

usage:     jmetadata.py inDirPath outFilePath
example:   jmetadata.py "\\Hal\hal free agent 1\backups\videos\" out.txt


>

However, when I copy the example to the command line I EXPECT the program to RUN. Instead I get:

>jmetadata.py "\\Hal\hal free agent 1\backups\videos\" out.txt
['\\\\Hal\\hal free agent 1\\backups\\videos" out.txt']

usage:     jmetadata.py inDirPath outFilePath
example:   jmetadata.py "\\Hal\hal free agent 1\backups\videos\" out.txt

Note the SECOND LINE in the above. That results from the print args command inside main(). It is saying that the args list has only 1 element, ['\\\\Hal\\hal free agent 1\\backups\\videos" out.txt'], instead of 2. This doesn’t make sense to me.

I have done a bit more investigation by writing a windows .cmd file. Here is show_args.cmd:

rem show_args.cmd
echo %1 
echo %2

Here is the result of a run:

>show_args.cmd "\\Hal\hal free agent 1\backups\videos\" out.txt

>rem show_args.cmd

>echo "\\Hal\hal free agent 1\backups\videos\"
"\\Hal\hal free agent 1\backups\videos\"

>echo out.txt
out.txt

Windows seems to separate the items. I am stumped. Does anyone know what’s goin on here?

I hope someone has some insight to share. Thanks in advance.

Answer 1

Try removing the trailing backslash. Change this:

jmetadata.py "\\Hal\hal free agent 1\backups\videos\" out.txt

to this:

jmetadata.py "\\Hal\hal free agent 1\backups\videos" out.txt

In your test run above, the arguments seen by Python are:

['\\\\Hal\\hal free agent 1\\backups\\videos" out.txt']

The trailing backspace is being interpreted as an escape character since it is immediately preceding a ", which turns your arguments into a single string (or until an unescaped " is encountered).