File descriptors python

This might seem simple when phrased but can cause a huge trauma to the programmer who has invested hours in writing the code. First, make sure that the specifies file descriptors are available in the console in which you run your program.

One way of handling this error is to calmly ignore the print statements and use alternative segments of code that serve a similar purpose. This error is caused when you specify a function to get executed when it has already completed doing the job. For instance, you order your code to close a file through your long lines of code.

It shows an error like:. It means that the file defined in the program is already closed automatically while running the code. There lies no use in defining a separate method to perform the same task again. During such an error, you should look for possibilities where your file may get closed in your code. In python file descriptors are integers positive that do the job of identifying the open files kept in a table of files by the kernel.

They are generally non-negative values 0, 1, or 2. Bad file descriptor mainly arises due to many factors that were discussed in brief above. The main fact is that they occur when the right functions do not perform in association with the file descriptors. With clear analysis and better knowledge of the concept, one can easily detect these errors and transform the code into a successful one.

IOError:[Errno 9] Bad file descriptor. Changed in version 3. Return the file descriptor associated with p as an int. If the object is an integer, its value is returned.

Sets an exception and returns -1 on failure. Equivalent to p. If n is 0 , exactly one line is read, regardless of the length of the line. If n is greater than 0 , no more than n bytes will be read from the file; a partial line can be returned. In both cases, an empty string is returned if the end of the file is reached immediately.

If n is less than 0 , however, one line is read regardless of length, but EOFError is raised if the end of the file is reached immediately. Overrides the normal behavior of io. The userData pointer is passed into the hook function. Add a comment. Active Oldest Votes. One call to open should correspond to one open file descriptor. I don't see it either. But this is a good example of why you should explicitly close files that you really want closed. Keith Keith Community Bot 1 1 1 silver badge.

Mark Byers Mark Byers k gold badges silver badges bronze badges. Something to add, to point out here, is that in the first instance, the file descriptor object is not returned, the contents of the file is.

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