how to change os.popen4 to subprocess
Prasad, Ramit
ramit.prasad at jpmorgan.com
Tue Oct 30 10:47:52 EDT 2012
Replying to skyworld because I could not find the original message
from MRAB.
skyworld wrote:
> On Oct 27, 11:02 am, MRAB <pyt... at mrabarnett.plus.com> wrote:
> > On 2012-10-27 03:28, skyworld wrote:> Hi,
> >
> > > I'm new to python and I'm trying to porting some scripts from v0.96 to
> > > v2.0.1. A piece of code is like this:
> >
> > > cmd_h = os.popen4(env['SYSCMDLINE'])[1]
> >
> > > the system indicates the popen4 is deprecated and suggest to use
> > > subprocess. Can anybody tell me how to use subprocess in this case?
> > > and what does "[1]" here means?
> >
> > os.popen4 returns a tuple of (child_stdin, child_stdout_and_stderr).
> > The [1] gets the child_stdout_and_stderr member.
> >
> > Using the subprocess module:
> >
> > # Untested!
> > cmd_h = subprocess.Popen(env['SYSCMDLINE'], stdout=subprocess.PIPE,
> > stderr=subprocess.STDOUT, shell=True).stdout
> >
> > Explanation:
> >
> > The command line: env['SYSCMDLINE']
> >
> > Return stdout: stdout=subprocess.PIPE
> >
> > stderr should be combined with stdout: stderr=subprocess.STDOUT
> >
> > Let the shell parse the command line: shell=True
>
> thanks
> --
I thought the usage of shell=True is usually discouraged? The
subprocess documentation[0] should be helpful to figure it out.
"""
Warning: Invoking the system shell with shell=True can be a security
hazard if combined with untrusted input. See the warning under
Frequently Used Arguments for details.
"""
[0] http://docs.python.org/2/library/subprocess.html
Ramit
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