os.system question

[stanleyxu]

Hi All,

I am porting Perl script to Python script. Everything works fines until
calling os.system().

In my script, a number of DOS-commands will be executed.
for new_folder, old_folder in folder_array:
os.system('MD "' + new_folder + '"');
os.system('XCOPY "' + old_folder + '" "' + new_folder + '"');

In Perl, all outputs will be printed in console directly.
But in Python, outputs will be printed in separated cmd-windows.

Is it possible to prevent so many cmd-windows to be opened and let all
output be printed direct in Python shell?


best regards ^^)
--
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oo // \\
(_,\/ \_/ \ Xu, Qian
\ \_/_\_/> stanleyxu2005
/_/ \_\

 

[kyosohma]

To note this problem occurs when debugging script in IDLE editor.
When I double click on my_script.py, all outputs will be printed in one
console.

--
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oo // \\
(_,\/ \_/ \ Xu, Qian
\ \_/_\_/> stanleyxu2005
/_/ \_\

Why are you using os.system for these commands in the first place? You
should be using the os and shutil modules instead as they would be
more cross-platform friendly.

Something like this:

# untested
for new_folder, old_folder in folder_array:
os.mkdir(new_folder)
shutil.copytree(old_folder, new_folder)


Adjust the path as needed in the mkdir call.

See shutil's docs for more info:
http://docs.python.org/lib/module-shutil.html

And here's some folder manipulation docs:
http://effbot.org/librarybook/os.htm

By the by, the subprocess module is supposed to be used in place of
the os.system and os.popen* calls: http://docs.python.org/lib/module-subprocess.html

Mike

 

[stanleyxu]

Why are you using os.system for these commands in the first place? You
should be using the os and shutil modules instead as they would be
more cross-platform friendly.

Something like this:

# untested
for new_folder, old_folder in folder_array:
os.mkdir(new_folder)
shutil.copytree(old_folder, new_folder)


Adjust the path as needed in the mkdir call.

See shutil's docs for more info:
http://docs.python.org/lib/module-shutil.html

And here's some folder manipulation docs:
http://effbot.org/librarybook/os.htm

By the by, the subprocess module is supposed to be used in place of
the os.system and os.popen* calls: http://docs.python.org/lib/module-subprocess.html

Mike

Thanks Mike,

you have provided another option.

But my question has not been answered yet. The reason, why I use
os.system(), is that I want to avoid accident file deletion by writing a
script. My real script looks like:

# 1. Funtion to execute a command in DOS-console
def execCommand(cmd):
if DEBUG_MODE:
print 'DOS> ' + cmd;
else:
os.system(cmd);

# 2.1 Creates temp folder. Removes it first, if it exists.
if os.path.exists(tmp_folder):
execCommand('RD "' + tmp_folder + '" /S /Q');
execCommand('MD "' + tmp_folder + '"');

# 2.2 Copies all files to the temp folder, that are going to be put in
package.
for source_folder, dest_folder in folders_array:
if not os.path.exists(dest_folder):
execCommand('MD "' + dest_folder + '"');
execCommand('XCOPY \"' + source_folder + '" "' + dest_folder + '" /Y');


The benefit is that, when I set DEBUG_MODE=True, I can see what will be
executed. So that I can make sure that my script will not delete any
other important files by accident.

--
___
oo // \\
(_,\/ \_/ \ Xu, Qian
\ \_/_\_/> stanleyxu2005
/_/ \_\

 

[Carl Banks]

Hi All,

I am porting Perl script to Python script. Everything works fines until
calling os.system().

In my script, a number of DOS-commands will be executed.
for new_folder, old_folder in folder_array:
os.system('MD "' + new_folder + '"');
os.system('XCOPY "' + old_folder + '" "' + new_folder + '"');

In Perl, all outputs will be printed in console directly.
But in Python, outputs will be printed in separated cmd-windows.

Is it possible to prevent so many cmd-windows to be opened and let all
output be printed direct in Python shell?

Consider using the subprocess module instead. It has more options
available than os.system, including I/O redirection, which seems to be
what you need.

In IDLE, you'll have to capture the output of the programs and print
it yourself, since you can't (AFAIK) run a DOS shell in an IDLE
window. Untested:


import subprocess

output = subprocess.Popen('MD "' + new_folder + '"', shell=True,
stdout=subprocess.PIPE, stderr=subprocess.STDOUT).communicate()[0]
print output


Carl Banks

 

[kyosohma]

Thanks Mike,

you have provided another option.

But my question has not been answered yet. The reason, why I use
os.system(), is that I want to avoid accident file deletion by writing a
script. My real script looks like:

Technically speaking, the shutil module's copytree function will not
delete ANYTHING if the destination already exists. It will just fail.
You could catch the failed copy with a try/except that prints an
appropriate message detailing the error.

# 1. Funtion to execute a command in DOS-console
def execCommand(cmd):
if DEBUG_MODE:
print 'DOS> ' + cmd;
else:
os.system(cmd);

# 2.1 Creates temp folder. Removes it first, if it exists.
if os.path.exists(tmp_folder):
execCommand('RD "' + tmp_folder + '" /S /Q');
execCommand('MD "' + tmp_folder + '"');

# 2.2 Copies all files to the temp folder, that are going to be put in
package.
for source_folder, dest_folder in folders_array:
if not os.path.exists(dest_folder):
execCommand('MD "' + dest_folder + '"');
execCommand('XCOPY \"' + source_folder + '" "' + dest_folder + '" /Y');

The benefit is that, when I set DEBUG_MODE=True, I can see what will be
executed. So that I can make sure that my script will not delete any
other important files by accident.

--
___
oo // \\
(_,\/ \_/ \ Xu, Qian
\ \_/_\_/> stanleyxu2005
/_/ \_\

Carl Banks mentioned the subprocess module too and he pointed out its
output redirection capabilities. I recommend checking those out too.
You may be able to do some redirection by changing where stdout and
stderr print to.

Mike

 

[stanleyxu]

Thanks again for your kindly tips.

--
___
oo // \\
(_,\/ \_/ \ Xu, Qian
\ \_/_\_/> stanleyxu2005
/_/ \_\

 

[stanleyxu]

import subprocess

output = subprocess.Popen('MD "' + new_folder + '"', shell=True,
stdout=subprocess.PIPE, stderr=subprocess.STDOUT).communicate()[0]
print output


Carl Banks

Thanks Carl, it works ^^)

--
___
oo // \\
(_,\/ \_/ \ Xu, Qian
\ \_/_\_/> stanleyxu2005
/_/ \_\