Python: need to pass quoted string to an exec call; prob w/ escaped chars

BrianK · 12-22-2008, 03:31 PM

I need to run this on the command line:

Code:

./prog -command 'trace("foo")'

... but it needs to be run by python, so I'm trying assemble the args & run like so:

Code:

  args = ['prog','-command \'trace("foo")\'']
  os.execvp("prog",args)

but I keep getting errors that seem to be related to the escaping of quotes and such. For example:

Code:

['prog', '-command \\\'trace("hello")\\\'']
Unmatched '.

  ----  or ----

['prog', '-command \'trace(\\"hello\\")\'']
Badly placed ()'s.

Not quite sure how to do this.

If I run from the command line, this works:

./prog -command 'trace("foo")'

so how can I get that to happen from within python?

indienick · 12-22-2008, 03:35 PM

My suggestion would be to use double-quotes instead of single-quotes, as single-quotes do not allow escape characters.

Code:

['prog', "-command \'trace(\"hello\")\'"]

BrianK · 12-22-2008, 05:30 PM

Quote:

Originally Posted by indienick

My suggestion would be to use double-quotes instead of single-quotes, as single-quotes do not allow escape characters.

Code:

['prog', "-command \'trace(\"hello\")\'"]

Rest assured, I've tried all the possible incarnations of quotes.

ghostdog74 · 12-22-2008, 07:35 PM

you can try the subprocess module. see the docs for examples

BrianK · 12-22-2008, 07:49 PM

Quote:

Originally Posted by ghostdog74

you can try the subprocess module. see the docs for examples

Specifically, what does the subprocess module accomplish that execvp doesn't with regards to the formatting of arguments? I'm pretty familiar with the subprocess module, but I'm not seeing it as a path to a solution to this problem (but will be happily corrected if I'm wrong)