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Python OSError

Python’s OS module offers tools for communicating with the operating system. OS is included in the basic utility modules for Python. A portable method of accessing operating system-specific functionality is offered by this module. There are numerous functions to deal with the file system in the ‘os’ and ‘os.path’ modules. The OS module’s functions help with tasks involving files, directories, and other OS-related tasks. When unreachable file names or paths or improper inputs are passed to this module’s functions, they all trigger an OSError. This error will be thoroughly covered in this post. We will help you identify the main causes of this error and ways to deal with it. In the article that discusses the OSError and the best way to fix it, some code examples are also included.

What is OSError?

The OS module’s error class and a built-in exception in Python are called OSError. When a system failure causes an error, it is raised. OSErrors are also a result of I/O problems.

OSError is also triggered in a case when the disk is full or maybe the file cannot be located. BlockingIOError, ConnectionError, ChildProcessError, FileExistsError, FileNotFoundError, etc. are examples of OSError subclasses.

There are two constructors for the OSError exception. As a result, the programmer can get an OSError description in one of two types:

  • exception OSError([arg])
  • exception OSError(errno, strerror[, filename[, winerror[, filename2]]])

The arguments are explained in the following section.

Error code in numerical form is the parameter ‘errno’. The second option is called ‘strerror,’ which is the operating system’s equivalent error message. For errors that occur in file system path-related routines or anything else affecting file paths, the ‘filename/filename2’ parameters are set. The Windows OS is the only one that supports the ‘winerror’ argument.

If not specified, the parameters are set to null. The subclass of OSError that the constructor returns depending on the final value of ‘errno.’

You now understand why the OSError arises. Let’s talk about some programming examples in the part that follows.

Example 1: 

Here’s an example of an OSError. You can see the ‘os’ module, which is necessary for many Python programs that work with files and directories. You can see that the print statement is used in the second line to obtain the terminal device connected to the provided file descriptor using Python’s s.ttyname() method. If the given file descriptor is not connected to any terminal devices, this code generates an exception.

import os as s

print(s.ttyname(4))

As you can see in the attached image below, the preceding code does not execute successfully and results in an error.

Below you can find some more examples that will discuss the OSError concept further.

Example 2: 

In this section, we’ll look at yet another OSError example before moving on to how to fix it. It is the OSError: [errno22] invalid argument example program. It occurs because an invalid argument is implied by OSError [Errno 22]. The error specifically indicates that the issue happens while reading, writing, or saving a file. You will find more details on this in the preceding lines here.

When using the open() function to open files, we may receive the error message ‘OSError: [errno22] invalid argument’ error. To work with a specific file in Python, you need to open the file for that. The open() function accomplishes what its name suggests by opening a file for you to use. A file object is returned. We can thus open the file in read-only, write-only, create-only, or append-only modes.

Let’s use some example program code to understand the error. We will attempt to use the open() method to open the file “demo.txt” in read-only mode. This is the sample file that we have created on our system. When the open() function is called, it will return the file as an object and save it in the variable named ‘save_here’.

The two lines of code are provided below. We imported the pandas module in the first line of the code. After that, we used the open() function to access a specific file for the purpose of reading. Here, you can also see the correct path which is specified.

import pandas as pd

save_here = open("pC:\\Users\\Kalsoom\\Desktop\\demo.txt","r")

The code throws the below error in which you can check [Errno 22] an invalid argument and the file path is also mentioned.

Python is unable to reach the path, causing the OSError: [errno22] invalid argument error to be thrown. It could be due to a typo, like a backslash, in the path that was given.

Example 3: 

In the code image below, we’ll see another os.error example. In this, we’ll demonstrate how to fix the OSError issue. View the code in the screenshot that is attached and read the explanation that is given below.

We imported the os module first. Following that, we executed OS methods using the try block. Here, we declare a variable called “Path” that holds the precise location of the file. We open the file using the os.open() method and we then declare a variable called “Descriptor” to hold its file descriptor (see the 4th line of the code). The except block was used in the last few lines to handle any os.error exceptions.

An os.error exception will be generated when we attempt to open the file “demo.txt.” The except block will catch this exception. The message “Error on the specified file:” will then be printed to the console.

import os

try:

  Path = 'pC:\\Users\\RABIA\\Desktop\\demo.txt'

  Descriptor = os.open(Path, os.O_RDWR)

  os.close(Descriptor)

except os.error:

  print("Error in the specified file:", Path)

Here, you see the output which shows the message given in the code.

Conclusion 

Exceptions in Python applications can occur for a variety of causes and lead to program crashes that result in data loss or, worse, corrupted data If they aren’t handled properly. You must consider potential exception scenarios as a Python developer and incorporate error handling into your code. One of the various exceptions that Python might throw is the OSError, which we’ve covered in-depth with examples.

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Source: linuxhint.com

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