Python: Python: SYS module

Snipplr-25248.py

# The sys module provides an interface to access the environment of the Python interpreter.
# The following examples illustrate some of the most common uses of the sys module.

# The argv attribute of the sys module is a list. The first item in the argv list is the 
# path to the module; the rest of the list is made up of arguments that were passed to the
# module at the beginning of execution. The sample code shows how to use the argv list to 
# access command-line parameters passed to a Python module:

>>>print sys.argv
['C:\\books\\python\\CH1\\code\\print_it.py',
'text']
>>>print sys.argv[1]
text

# The stdin attribute of the sys module is a file object that gets created at the start of
# code execution. In the following sample code, text is read from stdin (in this case, the
# keyboard, which is the default) using the readline() function:

>>>text = sys.stdin.readline()
>>>print text
Input Text

# The sys module also has the stdout and stderr attributes that point to files used for
# standard output and standard error output. These files default to writing to the screen.
# The following sample code shows how to redirect the standard output and standard error 
# messages to a file rather than to the screen:

>>>sOUT = sys.stdout
>>>sERR = sys.stderr
>>>sys.stdout = open("ouput.txt", "w")
>>>sys.stderr = sys.stdout
>>>sys.stdout = sOUT
>>>sys.stderr = sERR