how to change os.popen4 to subprocess

[skyworld]

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?

thanks.

 

[MRAB]

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

 

[Mark Lawrence]

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:

What software are you talking about here, it's certainly not Python
versions as the most up to date are 2.7.3 and 3.3.0?

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?

If you don't know what the [1] means you've got problems I suggest
you read the tutorial here first
http://docs.python.org/tutorial/index.html then the subprocess module
here http://docs.python.org/library/subprocess.html#module-subprocess,
specifically
http://docs.python.org/library/subprocess.html#subprocess-replacements

thanks.

No problem.

 

[skyworld]

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

 

[Prasad, Ramit]

Replying to skyworld because I could not find the original message
from MRAB.

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 andsuggest 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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