python3 -c with long cmd string: Trying to resolve invalid syntax

Question

I know it would be easier if I put a long python script within a file, but I am trying to resolve why I am having a syntax error when within a python3 -c cmd:

FYI: If it matters, I am performing this on OS X.

I read the following, but it did not resolve my problem: python multiline command running from bash

This is the working python3 script if executed from within a file:

import csv

with open('tmp/google_adwords_report.csv', 'r') as csvfile:
    csvfile.seek(0)
    next(csvfile)
    readCSV = csv.DictReader(csvfile)
    for row in readCSV:
        print(row)

And this is the same script if performed within command line python3 -c cmd:

$ python3 -c "import csv;  with open('tmp/google_adwords_report.csv', 'r') as csvfile: csvfile.seek(0); next(csvfile);  readCSV = csv.DictReader(csvfile); for row in readCSV: print(row);"

  File "<string>", line 1
    import csv;  with open('tmp/google_adwords_report.csv', 'r') as csvfile: csvfile.seek(0); next(csvfile);  readCSV = csv.DictReader(csvfile); for row in readCSV: print(row);
                    ^
SyntaxError: invalid syntax

Thanks

Based on the link you provided, you aren't exactly following the instructions in the working solution. I followed them and the only issue I had before getting it to work were indentation issues, which wasn't surprising. I tried out spacing accordingly after each\n and I got it working. By working...I did not receive a syntax error. That is all I checked as far as functionality. — idjaw
– idjaw, Commented Mar 23, 2016 at 22:09
Unrelated but csvfile.seek(0) is a noop, the pointer is already at the start of the file, also if you exec the line in an ide you will get the same error. I got it working correctly by adding tabs and newlines where necessary — Padraic Cunningham
– Padraic Cunningham, Commented Mar 23, 2016 at 22:17
@idjaw I tried: python3 -c "import csv\n\nwith open('tmp/google_adwords_report.csv', 'r') as csvfile:\n\tnext(csvfile)\n\treadCSV = csv.DictReader(csvfile)\n\tfor row in readCSV:\n\t\tprint(row)", and I got SyntaxError: unexpected character after line continuation character — jeff00seattle
– jeff00seattle, Commented Mar 23, 2016 at 22:30
@JeffTanner That means your spacing after the new lines is still off. This did not give me a syntax error: pastebin.com/WPPaFKEx — idjaw
– idjaw, Commented Mar 23, 2016 at 22:32

Brian · Accepted Answer · 2016-03-23 22:23:42Z

2

You are limited by what is allowed in Python on a single line. See the Compound Statements section of the Python Language Ref for more info.

Basically, some things are not allowed. For example:

python -c "if (1): print(1)"

is okay. But:

python -c "if (1): if (1): print(1)"

is not allowed.

Another thing, you can't combine a statement with a indented clause. So, this is also not okay:

python -c "print(1); if (1): print(1)"

And that's the issue you are running into.

If you're in a shell that supports continuation of strings, you could do:

# python3 -c "if (1):
>   if (1):
>     print(1)
> "
1

Another thing that may work for you is inline CRs (via ^V^M). For example:

# python3 -c "if (1):^M  if (1):^M    print(1)"
1

That is, I actually typed in CTRL-V CTRL-M to create the ^M.

And, I am on OS X as well (Mavericks), running from bash.

edited Mar 23, 2016 at 22:23

answered Mar 23, 2016 at 22:18

Brian

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Comments

miken32 · Accepted Answer · 2016-03-24 16:48:37Z

1

Tyring to do this in a single line is wasting your time, and will cause you grief when you need to make a change to your code. This would be true in any language, but is especially so due to Python's whitespace requirements.

Just use a heredoc:

python3 << EOF
import csv

with open('tmp/google_adwords_report.csv', 'r') as csvfile:
    csvfile.seek(0)
    next(csvfile)
    readCSV = csv.DictReader(csvfile)
    for row in readCSV:
        print(row)
EOF

answered Mar 24, 2016 at 16:48

miken32

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