What is Python stderr?
This file handle receives error information from the user program. The Standard error returns errors stderr. we will see different examples of using stderr.
Method 1: Using Python stderr
It is comparable to stdout in that it likewise prints straight to the console, but the key distinction is that it prints only Exceptions and Error messages which is why it is called Standard Error in Python.
Python3
import sysdef 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") |
Output:
Method 2: Using Python sys.stderr.write() function
When used in interactive mode, sys.stderr.write() accomplishes the same task as the object it stands for, with the exception that it also prints the text’s letter count.
Python3
import sysprint("Example 1")print("Example 2", file=sys.stderr)sys.stderr.write("Example 3") |
Output:
Method 3: Using Python logging.warning function
A built-in Python package tool called logging.warning enables publishing status messages to files or other output streams. The file may provide details about which portion of the code is run and any issues that have come up.
Python3
import logginglogging.basicConfig(format='%(message)s')log = logging.getLogger(__name__)log.warning('Error: Hello World')print('w3wiki') |
Output:
Error: Hello World w3wiki
How to print to stderr and stdout in Python?
In Python, whenever we use print() the text is written to Python’s sys.stdout, whenever input() is used, it comes from sys.stdin, and whenever exceptions occur it is written to sys.stderr.
We can redirect the output of our code to a file other than stdout. But you may be wondering why one should do this? The reason can be to keep a log of your code’s output or to make your code shut up i.e. not sending any output to the stdout. Let’s see how to do it with the below examples.
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