[python-win32] os.system problem

Wed May 7 16:04:58 EDT 2003

Things seem to work fine for me:

jbj1 at tallan2 /c/temp
$ mkdir /c/cygwin/test\ folder

jbj1 at tallan2 /c/temp
$ cp /usr/bin/grep.exe /c/cygwin/test\ folder/

jbj1 at tallan2 /c/temp
$ python
ActivePython 2.2.2 Build 224 (ActiveState Corp.) based on
Python 2.2.2 (#37, Nov 26 2002, 10:24:37) [MSC 32 bit (Intel)] on win32
Type "help", "copyright", "credits" or "license" for more information.
 >>> import os
 >>> os.chdir('/cygwin')
 >>> os.system('test folder/grep.exe')
0
 >>> os.system('"test folder/grep.exe"')
Usage: grep [OPTION]... PATTERN [FILE]...
Try `grep --help' for more information.
2
 >>> os.system('"test folder/grep.exe" --?')
grep: unknown option -- ?
Usage: grep [OPTION]... PATTERN [FILE]...
Try `grep --help' for more information.
2
 >>> os.system('"test folder/grep.exe" "bleh"')
0
 >>>

Are you using cygwin's python or ActiveState's?

Lawrence W. Leung wrote:

>Hi,
>
>I'm trying to use os.system to execute a command in win2k with python
>2.2.2 and it's not behaving as expected.  Basically, the idea is I pass it
>a command line that begins with a quoted path to an executable (to avoid
>the problem of the space in the path) and also a quoted argument and it
>fails to find the executable.  But oddly enough when I unquote the
>argument it seems to find the executable just fine.
>
>I've been playing with this for quite a while now and I'm starting to
>suspect it's a python bug.  When I print out my command, it shows up fine.
>I can even copy that into a cmd.exe window and have it run fine.  But when
>I run it with python and it doesn't work.  Can someone try to reproduce
>this problem to check if it's really a bug?
>
>Here's a simplified test case using cygwin's grep:
>1. copy grep.exe into a new folder "test folder" in your cygwin dir.
>2. in python, os.chdir() into the cygwin dir.
>3. os.system('test folder/grep.exe') returns 1 for me (can't find exe)
>4. os.system('"test folder/grep.exe"') returns 128 for me (grep can't find
>a cygwin dll
>5. os.system('"test folder/grep.exe" --?') returns 128 for me (as
>expected)
>6. os.system('"test folder/grep.exe" "bleh"') returns 1 for me!! (command
>not found!)
>
>Thanks,
>----
>-Larry
>
>On Tue, 6 May 2003, Raymond Hettinger wrote:
>
>  
>
>>Hello Larry,
>>
>>Using quotes and escape characters can work but that is
>>taking the hard around.
>>
>>I recommend several things that will simplify solving problems
>>like this.
>>
>>First, get the string logic right (verified with a print
>>statement) before adding the os.system command and trying
>>to guess what was sent to the interpreter.
>>
>>Second, debug your string logic using the interactive interpreter.
>>This is the easiest way to see what works and avoids having
>>to use print to see what is going on.
>>
>>Third, avoid escape character issues by using either:
>>   - raw strings:   r"the \quick"
>>   - outer quotes of a different type  'he said hello" to me'
>>   - triple quotes """Here are the "do's and don'ts" of quoting"""
>>
>>Taken together the three ideas ought to make the problem trivial:
>>
>>    
>>
>>>>>command = 'c:/program files/utils/grep "'
>>>>>command
>>>>>          
>>>>>
>>'c:/program files/utils/grep "'
>>    
>>
>>>>>argument = 'search text'
>>>>>argument
>>>>>          
>>>>>
>>'search text'
>>    
>>
>>>>>fullcommand = command + argument + '"'
>>>>>fullcommand
>>>>>          
>>>>>
>>'c:/program files/utils/grep "search text"'
>>    
>>
>>>>>import os
>>>>>os.system(fullcommand)
>>>>>          
>>>>>
>>
>>Raymond Hettinger
>>
>>
>>
>>----- Original Message -----
>>From: "Lawrence W. Leung" <larryl at imail.CS.Berkeley.EDU>
>>To: <help at python.org>
>>Cc: "Lawrence W. Leung" <larryl at imail.CS.Berkeley.EDU>
>>Sent: Tuesday, May 06, 2003 5:34 PM
>>Subject: Re: [Python-Help] os.system problem
>>
>>
>>    
>>
>>>Sorry, I think you misunderstood me.
>>>
>>>The full code to build the command looks something like this:
>>>COMMAND = "\"C:/Program Files/...exe\""
>>>os.system(COMMAND+" \"argument\"")
>>>
>>>It shouldn't matter that I'm using quotes and escape chars right?
>>>Thanks,
>>>-Larry
>>>
>>>      
>>>
>>>>>I'm using 2.2.2 on windows and I noticed that os.system doesn't
>>>>>seem to be working like a command line would.
>>>>>          
>>>>>
>>>>>If i call: "C:/Program Files/...some.exe", it works
>>>>>If i call: "C:/Program Files/...some.exe" some arguments, it works
>>>>>but if I call: "C:/Program Files/...some.exe"
>>>>>"some-argument-in-quotes",
>>>>>it complains about not being able to find the executable C:/Program
>>>>>          
>>>>>
>>>>Python can use either single or double quotes (actually, it can use
>>>>triple-quotes too). So something like:
>>>>
>>>>cmd='c:/Program Files/wibble.exe "args"'
>>>>os.system(cmd)
>>>>
>>>>ought to work.
>>>>
>>>>Regards,
>>>>Matt
>>>>
>>>>
>>>>        
>>>>
>>>_______________________________________________
>>>Python-Help maillist  -  Python-Help at python.org
>>>http://mail.python.org/mailman/listinfo/python-help
>>>      
>>>
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>>
>>    
>>
>
>
>
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-- 
Jens B. Jorgensen
jens.jorgensen at tallan.com

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