# 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

## 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

Python: SYS module

python

Python