16

I am running a script which takes a text "rAh%19u^l\&G" i.e which contains special characters as seen.

When i pass this text in my script as a argument it runs fine without any error.

example - : ./abc.py <username><pwd>

The above text is basically a password.

Now, when i place my values in a config file and read the above text, the script fails.

*******abc.ini *******

[DEFAULT]
username = rahul
pwd =  rAh%19u^l\&G

it says

/bin/sh:M command not found.

Reading the above values with help of config parser

******Below is the program abc.py ******

#! /usr/bin/python

parser = configparser.ConfigParser()
parser.read('abc.ini')
username = parser.get('DEFAULT','username')
pwd = parser.get('DEFAULT','pwd')


p = subprocess.Popen(
    "abc.py {0} {1}" .format(username, pwd), 
    shell=True, 
    stdout=subprocess.PIPE
)

out, err = p.communicate()

print(out)

I tried searching a lot but found nothing concrete.

So the question is how to read a text that contains special characters in a .ini file.

Paulo Scardine
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Rahul Gupta
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  • Don't format code with backticks in questions. Instead indent by 4 spaces (with leading newline). You can do this automatically by highlighting your code and pressing the `{}` button at the top. – internet_user Dec 04 '17 at 19:17
  • Have you tried quoting it as in `pwd = "rAh%19u^l\&G"` or escaping the backslash as in `pwd = "rAh%19u^l\\&G"` - btw, what is the value of `username` and `pwd`, can you print them before calling the other script? – Paulo Scardine Dec 04 '17 at 19:17
  • @PauloScardine - i tried rAh%19u^l\\&G by using backslash but it didn't work out.i didn't tried quoting it. But while quoting it won't it take quotes also as complete text ?? – Rahul Gupta Dec 04 '17 at 19:21
  • Try that and tell us... :-) – Paulo Scardine Dec 04 '17 at 19:24
  • @PauloScardine My sincere apologies will be much careful from next time as i post a question . As suggested tried both "rAh%19u^l\&G" and pwd = "rAh%19u^l\\&G" both didn't work . i will use the RawConfigParser and then share my results – Rahul Gupta Dec 04 '17 at 19:46

4 Answers4

27

Looks like the % character is the problem here. It has special meaning if you are using ConfigParser. If you are not using interpolation, then use just RawConfigParser instead, otherwise you must escape the % by doubling it.

When I try the example file with ConfigParser it will blow with the following exception: 

InterpolationSyntaxError: '%' must be followed by '%' or '(', found: '%19u^l\\&G"'

If I replace ConfigParser with RawConfigParser everything is fine.

The error you posted has nothing to do with it. We can't even tell if it is a python exception or a shell error message. Please update your question with the full error message. You may also want to check the sh module, a higher level wrapper around subprocess.

Paulo Scardine
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  • ...a big thanks for the answer. This worked. I was searching this since last week. The RawConfigParser just worked fine. – Rahul Gupta Dec 05 '17 at 07:41
  • One is glad to be of service, sire. – Paulo Scardine Dec 05 '17 at 13:20
  • as @Ativerc mentioned, [`RawConfigParser`](https://docs.python.org/3.6/library/configparser.html#configparser.RawConfigParser) is a "Legacy variant of the ConfigParser with interpolation disabled by default and unsafe add_section and set methods." – arturomp May 04 '21 at 19:07
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    Consider using `ConfigParser` instead which checks types of the values to be stored internally. If you don’t want interpolation, you can use `ConfigParser(interpolation=None)`. – newcool Mar 23 '22 at 06:28
4

Adding up on Paulo Scardine's comment.

if you have special characters that need to be handled, you can set the ConfigParser's interpolation argument to None and you won't have the error anymore. ConfigParser has interpolation set to BasicInterpolation() by default.

You can read more about this here: https://docs.python.org/3.6/library/configparser.html#interpolation-of-values

Further, as per the docs RawConfigParser is a Legacy variant of the ConfigParser with interpolation disabled by default and unsafe add_section and set methods.

Here's a snippet from there:

Example:

[Paths]
home_dir: /Users
my_dir: %(home_dir)s/lumberjack
my_pictures: %(my_dir)s/Pictures

In the example above, ConfigParser with interpolation set to BasicInterpolation() would resolve %(home_dir)s to the value of home_dir (/Users in this case). %(my_dir)s in effect would resolve to /Users/lumberjack. [....]

With interpolation set to None, the parser would simply return %(my_dir)s/Pictures as the value of my_pictures and %(home_dir)s/lumberjack as the value of my_dir.

Ativerc
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1

you could escape the special char with same char. for example, to be able to read % you have to write it %%

Mustafa thamer
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  • How does this work with a single quote `'`? I have an apostrophe in a folders name, but configparser can't seem to parse this – Swedgin Oct 21 '20 at 10:01
0

I had came across this same issue. Understandably the answer has been posted. Using the comments from everyone on this post I had resolved this issue with the following:

My password was Sgf%ts54hhGtrf&yhgf

alembic ini file I was using: sqlalchemy.url = driver://myuser:Sgf%ts54hhGtrf&yhgf@localhost/my_application

Error received: configparser.InterpolationSyntaxError: '%' must be followed by '%' or '(', which informs me the special character is '%'

Resolved the issue by just wrapping the password in a single quote and doubled the % symbol as recommended from comments in this post to end up with:

sqlalchemy.url = driver://myuser:'Sgf%%ts54hhGtrf&yhgf'@localhost/my_application

No need to worry about changing the ConfigParser as long as you stick to the rule of wrapping the password containing special characters with a single quote and any special characters found in the error you receive to double it e.g. if the error is related to a %, add another and end up with %%

Dharman
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Wick 12c
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