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This module allows you to spawn processes and connect to their
input/output/error pipes and obtain their return codes under
Unix and Windows.
The subprocess module provides more powerful facilities for
spawning new processes and retrieving their results. Using the
subprocess module is preferable to using the popen2
module.
The primary interface offered by this module is a trio of factory
functions. For each of these, if bufsize is specified,
it specifies the buffer size for the I/O pipes. mode, if
provided, should be the string 'b' or 't'; on Windows
this is needed to determine whether the file objects should be opened
in binary or text mode. The default value for mode is
't'.
On Unix, cmd may be a sequence, in which case arguments will be passed
directly to the program without shell intervention (as with
os.spawnv()). If cmd is a string it will be passed to the
shell (as with os.system()).
The only way to retrieve the return codes for the child processes is
by using the poll() or wait() methods on the
Popen3 and Popen4 classes; these are only available on
Unix. This information is not available when using the
popen2(), popen3(), and popen4()
functions, or the equivalent functions in the os module.
(Note that the tuples returned by the os module's functions
are in a different order from the ones returned by the popen2
module.)
| popen2( |
cmd[, bufsize[, mode]]) |
-
Executes cmd as a sub-process. Returns the file objects
(child_stdout, child_stdin).
| popen3( |
cmd[, bufsize[, mode]]) |
-
Executes cmd as a sub-process. Returns the file objects
(child_stdout, child_stdin, child_stderr).
| popen4( |
cmd[, bufsize[, mode]]) |
-
Executes cmd as a sub-process. Returns the file objects
(child_stdout_and_stderr, child_stdin).
New in version 2.0.
On Unix, a class defining the objects returned by the factory
functions is also available. These are not used for the Windows
implementation, and are not available on that platform.
| class Popen3( |
cmd[, capturestderr[, bufsize]]) |
-
This class represents a child process. Normally, Popen3
instances are created using the popen2() and
popen3() factory functions described above.
If not using one of the helper functions to create Popen3
objects, the parameter cmd is the shell command to execute in a
sub-process. The capturestderr flag, if true, specifies that
the object should capture standard error output of the child process.
The default is false. If the bufsize parameter is specified, it
specifies the size of the I/O buffers to/from the child process.
| class Popen4( |
cmd[, bufsize]) |
-
Similar to Popen3, but always captures standard error into the
same file object as standard output. These are typically created
using popen4().
New in version 2.0.
Release 2.5.2, documentation updated on 21th February, 2008.
See About this document... for information on suggesting changes.
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