19 sys module in python

 

'''

1. Using sys module we can do system related operation.

'''

import sys

print(sys.version)

## to append path

#sys.path.append(r'C:\\Users\\sriram\\Desktop\\akr')

## To exit from execution

print(' \n Before exit')

sys.exit()

print(' \n After exit')

-------------Input and Output using sys

The sys modules provide variables for better control over input or output. 

We can even redirect the input and output to other devices. 

This can be done using three variables – 

1.stdin

2.stdout

3.stderr

----stdin---: It can be used to get input from the command line directly. 

It used is for standard input. 

It internally calls the input() method. 

It, also, automatically adds ‘\n’ after each sentence.

import sys

for line in sys.stdin:

    if 'q' == line.rstrip():

        break

    print(f'Input : {line}')

print("Exit")

--------stdout-------: A built-in file object that is  to 

the interpreter’s standard output stream in Python.

import sys

sys.stdout.write('umamahesh')

---------stderr------------: Whenever an exception occurs in Python 

it is written to sys.stderr. 

import sys

 

 

def print_to_stderr(*a):

 

    # Here a is the array holding the objects

    # passed as the argument of the function

    print(*a, file = sys.stderr)

 

print_to_stderr("Hello World")

Exiting the Program

sys.exit([arg]) can be used to exit the program

import sys

 

 

age = 17

 

 

if age < 18:

# exits the program

sys.exit("Age less than 18")    

else:

print("Age is not less than 18")

Working with Modules

sys.path is a built-in variable within the sys module 

that returns the list of directories that 

the interpreter will search for the required module.

import sys

print(sys.path)

## To get command line arguments

#first_com_arg = sys.argv[1]

#print(' first_com_arg is :', first_com_arg)