On Jul 16, 2008, at 1:28 AM, Glynn Clements wrote:
Michael Barton wrote:
subprocess.call([
"v.extract",
"input=%s" % os.getenv("GIS_OPT_INPUT"),
"output=%s_%s" % (os.getenv("GIS_OPT_OUTPUT"), i),
"type=point", "layer=1", "new=-1", "list=%s" % i])
Glynn,
How do subprocess.call and subprocess.Popen compare for running GRASS
commands from inside Python scripts? Is call easier than Popen in
this
context?
subprocess.call is a convenience function for the simplest case where
you don't need to interact with the child process beyond waiting for
it to finish; it's defined as:
def call(*args, **kwargs):
"""Run command with arguments. Wait for command to complete,
then
return the returncode attribute.
The arguments are the same as for the Popen constructor.
Example:
retcode = call(["ls", "-l"])
"""
return Popen(*args, **kwargs).wait()
It behaves like system(), but without the shell (so you don't have to
deal with /bin/sh syntax vs cmd.exe syntax, spaces and other shell
metacharacters in argument values, etc).
It's roughly equivalent to os.spawnvp(P_WAIT,...), which is deprecated
in favour of the subprocess module. Most of the other os.* functions
are similarly deprecated, except for the os.exec* family (for which
the main use is executing g.parser).
--
Glynn Clements <[EMAIL PROTECTED]>
This seems very handy for a lot of basic GRASS scipting, including
replacing bash scripts with Python ones--something that I'd like to
start on soon and would encourage anyone wanting to get experience in
Python to try.
Michael
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