How to erase the file contents of text file in Python

Question

I have text file which I want to erase in Python  How do I do that

User · Answer

Opening a file in  write  mode clears it  you don t specifically have to write to it   open  filename    w   close      you should close it as the timing of when the file gets closed automatically may be implementation specific

User · Answer

You have to overwrite the file  In C      include  lt fstream gt   std  ofstream  test txt   std  ios  out  close

User · Answer

Since text files are sequential  you can t directly erase data on them  Your options are    The most common way is to create a new file  Read from the original file and write everything on the new file  except the part you want to erase  When all the file has been written  delete the old file and rename the new file so it has the original name  You can also truncate and rewrite the entire file from the point you want to change onwards  Seek to point you want to change  and read the rest of file to memory  Seek back to the same point  truncate the file  and write back the contents without the part you want to erase  Another simple option is to overwrite the data with another data of same length  For that  seek to the exact position and write the new data  The limitation is that it must have exact same length    Look at the seek truncate function method to implement any of the ideas above  Both Python and C have those functions

User · Answer

When using with open  myfile txt    r    as my file   I get strange zeros in myfile txt  especially since I am reading the file first  For it to work  I had to first change the pointer of my file to the beginning of the file with my file seek 0   Then I could do my file truncate   to clear the file

User · Answer

Writing and Reading file content def writeTempFile text            filePath    quot  temp file1 txt quot      if not text                         If blank return file content         f   open filePath   quot r quot           slug   f read           return slug     else          f   open filePath   quot a quot     Create a blank file         f seek 0     sets  point at the beginning of the file         f truncate      Clear previous content         f write text    Write file         f close     Close file         return text  It Worked for me

User · Answer

From user  jamylak an alternative form of open  filename   w   close   is  with open  filename txt   w    pass

User · Answer

If security is important to you then opening the file for writing and closing it again will not be enough  At least some of the information will still be on the storage device and could be found  for example  by using a disc recovery utility   Suppose  for example  the file you re erasing contains production passwords and needs to be deleted immediately after the present operation is complete   Zero-filling the file once you ve finished using it helps ensure the sensitive information is destroyed   On a recent project we used the following code  which works well for small text files  It overwrites the existing contents with lines of zeros   import os  def destroy password file password filename       with open password filename  as password file          text   password file read       lentext   len text      zero fill line length   40     zero fill     0    zero fill line length                       for                         in range lentext    zero fill line length   1       zero fill   os linesep join zero fill      with open password filename   w   as password file          password file write zero fill    Note that zero-filling will not guarantee your security  If you re really concerned  you d be best to zero-fill and use a specialist utility like File Shredder or CCleaner to wipe clean the  empty  space on your drive

User · Answer

In python   open  file txt    w   close     Or alternatively  if you have already an opened file   f   open  file txt    r    f truncate 0    need  0  when using r    In C    you could use something similar

User · Answer

Assigning the file pointer to null inside your program will just get rid of that reference to the file  The file s still there  I think the remove   function in the c stdio h is what you re looking for there  Not sure about Python

User · Answer

Not a complete answer more of an extension to ondra s answer  When using truncate     my preferred method   make sure your cursor is at the required position  When a new file is opened for reading - open  FILE NAME   r   it s cursor is at 0 by default  But if you have parsed the file within your code  make sure to point at the beginning of the file again i e truncate 0  By default truncate   truncates the contents of a file starting from the current cusror position   A simple example

User · Answer

You can also use this  based on a few of the above answers   file   open  filename txt    w   file close    of course this is a really bad way to clear a file because it requires so many lines of code  but I just wrote this to show you that it can be done in this method too  happy coding

User · Answer

You cannot  erase  from a file in-place unless you need to erase the end  Either be content with an overwrite of an  empty  value  or read the parts of the file you care about and write it to another file

[python] How to erase the file contents of text file in Python?

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