Return to Answer

For convenience, Python 2.7 provides the

subprocess.check_output(*popenargs, **kwargs)  

function, which takes the same arguments as Popen, but returns a string containing the program's output. You can pass stderr=subprocess.STDOUT to ensure that error messages are included in the returned output -- but don't pass stderr=subprocess.PIPE to check_output. It can cause deadlocks. If you need to pipe from stderr, see the Popen example below.

If you're using an older python, Vartec's method will work. But the better way to go -- at least in simple cases that don't require real-time output capturing -- is to use communicate. As in:

output = Popen(["mycmd", "myarg"], stdout=PIPE).communicate()[0]

Or

>>> import subprocess
>>> p = subprocess.Popen(['ls', '-a'], stdout=subprocess.PIPE, 
...                                    stderr=subprocess.PIPE)
>>> out, err = p.communicate()
>>> print out
.
..
foo

If you set stdin=PIPE, communicate also allows you to pass data to the process via stdin:

>>> cmd = ['awk', 'length($0) > 5']
>>> p = subprocess.Popen(cmd, stdout=subprocess.PIPE,
...                           stderr=subprocess.PIPE,
...                           stdin=subprocess.PIPE)
>>> out, err = p.communicate('foo\nfoofoo\n')
>>> print out
foofoo

Finally, note Aaron Hall's answer, which indicates that on some systems, you may need to set stdout, stderr, and stdin all to PIPE (or DEVNULL) to get communicate to work at all.

For convenience, Python 2.7 provides the

subprocess.check_output(*popenargs, **kwargs)  

function, which takes the same arguments as Popen, but returns a string containing the program's output. You can pass stderr=subprocess.STDOUT to ensure that error messages are included in the returned output -- but don't pass stderr=subprocess.PIPE to check_output. It can cause deadlocks. If you need to pipe from stderr, see the Popen example below.

If you're using an older python, Vartec's method will work. But the better way to go -- at least in simple cases that don't require real-time output capturing -- is to use communicate. As in:

output = subprocess.Popen(["mycmd", "myarg"], stdout=subprocess.PIPE).communicate()[0]

Or

>>> import subprocess
>>> p = subprocess.Popen(['ls', '-a'], stdout=subprocess.PIPE, 
...                                    stderr=subprocess.PIPE)
>>> out, err = p.communicate()
>>> print out
.
..
foo

If you set stdin=PIPE, communicate also allows you to pass data to the process via stdin:

>>> cmd = ['awk', 'length($0) > 5']
>>> p = subprocess.Popen(cmd, stdout=subprocess.PIPE,
...                           stderr=subprocess.PIPE,
...                           stdin=subprocess.PIPE)
>>> out, err = p.communicate('foo\nfoofoo\n')
>>> print out
foofoo

Finally, note Aaron Hall's answer, which indicates that on some systems, you may need to set stdout, stderr, and stdin all to PIPE (or DEVNULL) to get communicate to work at all.

For convenience, Python 2.7 provides the

subprocess.check_output(*popenargs, **kwargs)  

function, which takes the same arguments as Popen, but returns a string containing the program's output. You can pass stderr=subprocess.STDOUT to ensure that error messages are included in the returned output -- but don't pass stderr=subprocess.PIPE, which can cause deadlocks. See here for more.

If you're using an older python, Vartec's method will work. But the better way to go -- at least in simple cases that don't require real-time output capturing -- is to use communicate. As in:

output = Popen(["mycmd", "myarg"], stdout=PIPE).communicate()[0]

Or

>>> import subprocess
>>> p = subprocess.Popen(['ls', '-a'], stdout=subprocess.PIPE, 
...                                    stderr=subprocess.PIPE)
>>> out, err = p.communicate()
>>> print out
.
..
foo

If you set stdin=PIPE, communicate also allows you to pass data to the process via stdin:

>>> cmd = ['awk', 'length($0) > 5']
>>> p = subprocess.Popen(cmd, stdout=subprocess.PIPE,
...                           stderr=subprocess.PIPE,
...                           stdin=subprocess.PIPE)
>>> out, err = p.communicate('foo\nfoofoo\n')
>>> print out
foofoo

Finally, note Aaron Hall's answer, which indicates that on some systems, you may need to set stdout, stderr, and stdin all to PIPE (or DEVNULL) to get communicate to work at all.

For convenience, Python 2.7 provides the

subprocess.check_output(*popenargs, **kwargs)  

function, which takes the same arguments as Popen, but returns a string containing the program's output. You can pass stderr=subprocess.STDOUT to ensure that error messages are included in the returned output -- but don't pass stderr=subprocess.PIPE to check_output. It can cause deadlocks. If you need to pipe from stderr, see the Popen example below.

If you're using an older python, Vartec's method will work. But the better way to go -- at least in simple cases that don't require real-time output capturing -- is to use communicate. As in:

output = Popen(["mycmd", "myarg"], stdout=PIPE).communicate()[0]

Or

>>> import subprocess
>>> p = subprocess.Popen(['ls', '-a'], stdout=subprocess.PIPE, 
...                                    stderr=subprocess.PIPE)
>>> out, err = p.communicate()
>>> print out
.
..
foo

If you set stdin=PIPE, communicate also allows you to pass data to the process via stdin:

>>> cmd = ['awk', 'length($0) > 5']
>>> p = subprocess.Popen(cmd, stdout=subprocess.PIPE,
...                           stderr=subprocess.PIPE,
...                           stdin=subprocess.PIPE)
>>> out, err = p.communicate('foo\nfoofoo\n')
>>> print out
foofoo

Finally, note Aaron Hall's answer, which indicates that on some systems, you may need to set stdout, stderr, and stdin all to PIPE (or DEVNULL) to get communicate to work at all.

For convenience, Python 2.7 provides the

subprocess.check_output(*popenargs, **kwargs)  

function, which takes the same arguments as Popen, but returns a string containing the program's output. You can pass stderr=subprocess.STDOUT to ensure that error messages are included in the returned output -- but don't pass stderr=subprocess.PIPE, which can cause deadlocks. See here for more.

If you're using an older python, Vartec's method will work. But the better way to go -- at least in simple cases that don't require real-time output capturing -- is to use communicate. As in:

output = Popen(["mycmd", "myarg"], stdout=PIPE).communicate()[0]

Or

>>> import subprocess
>>> p = subprocess.Popen(['ls', '-a'], stdout=subprocess.PIPE, 
...                                    stderr=subprocess.PIPE)
>>> out, err = p.communicate()
>>> print out
.
..
foo

If you set stdin=PIPE, communicate also allows you to pass data to the process via stdin; just remember to set stdin=PIPE.

>>> cmd = ['awk', 'length($0) > 5']
>>> p = subprocess.Popen(cmd, stdout=subprocess.PIPE,
...                           stderr=subprocess.PIPE,
...                           stdin=subprocess.PIPE)
>>> out, err = p.communicate('foo\nfoofoo\n')
>>> print out
foofoo

Finally, note Aaron Hall's answer, which indicates that on some systems, you may need to set stdout, stderr, and stdin all to PIPE to get communicate to work at all.

For convenience, Python 2.7 provides the

subprocess.check_output(*popenargs, **kwargs)  

function, which takes the same arguments as Popen, but returns a string containing the program's output. You can pass stderr=subprocess.STDOUT to ensure that error messages are included in the returned output -- but don't pass stderr=subprocess.PIPE, which can cause deadlocks. See here for more.

If you're using an older python, Vartec's method will work. But the better way to go -- at least in simple cases that don't require real-time output capturing -- is to use communicate. As in:

output = Popen(["mycmd", "myarg"], stdout=PIPE).communicate()[0]

Or

>>> import subprocess
>>> p = subprocess.Popen(['ls', '-a'], stdout=subprocess.PIPE, 
...                                    stderr=subprocess.PIPE)
>>> out, err = p.communicate()
>>> print out
.
..
foo

If you set stdin=PIPE, communicate also allows you to pass data to the process via stdin:

>>> cmd = ['awk', 'length($0) > 5']
>>> p = subprocess.Popen(cmd, stdout=subprocess.PIPE,
...                           stderr=subprocess.PIPE,
...                           stdin=subprocess.PIPE)
>>> out, err = p.communicate('foo\nfoofoo\n')
>>> print out
foofoo

Finally, note Aaron Hall's answer, which indicates that on some systems, you may need to set stdout, stderr, and stdin all to PIPE (or DEVNULL) to get communicate to work at all.