How to print to stderr in Python
This tutorial explains how to write to standard error output in Python stderr. It also lists some sample code to explain different ways to write stderr, as the syntax has changed over time.
In Python 3.x this printsstderr
For Python 3.x, printthe function has a keyword argument filethat specifies the destination for printing. The default is sys.stdout, but it can also be sys.stderr, or even a file path.
If file=sys.stderr, it will print the information to stderr. Here is a sample code.
import sys
print("Error", file=sys.stderr)
Output:
Error
In Python 2.x this printsstderr
For Python 2.x, printthe statement can print messages to a file-like target, such as stdout, stderror a file path. The file-like object is >>specified after . See the example below.
import sys
print >>sys.stderr, "Error Detected!"
Output:
Error Detected!
Use sys.stderrPrint Tostderr
Python's sysmodule provides valuable information and key functions. You can use sys.stderr.write()the method. sys.stderr.write()The method prints a message to the given argument stderr. See the following example.
import sys
sys.stderr.write("Error!")
Output:
Error!
Use loggingthe module to print tostderr
The module in Python loggingis specifically created for logging messages. The logging module can be used to set up basic configuration and then print to stderr. logging.basicConfig()It takes messagea format as input and logging.getLogger()returns an loggingobject. log.warning()It takes warningthe text and prints it to stderr.
A basic example looks like this:
import logging
logging.basicConfig(format="%(messages)s")
log = logging.getLogger()
log.warning("Error Found!")
Output:
Error Found!
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