How to delete only the content of file in python

Question

I have a temporary file with some content and a python script generating some output to this file  I want this to repeat N times  so I need to reuse that file  actually array of files   I m deleting the whole content  so the temp file will be empty in the next cycle  For deleting content I use this code   def deleteContent pfile        pfile seek 0      pfile truncate       pfile seek 0    I believe this seek is redundant      return pfile  tempFile deleteContent tempFile    My question is  Is there any other  better  shorter or safer  way to delete the whole content without actually deleting the temp file from disk   Something like tempFile truncateAll

User · Answer

I think the easiest is to simply open the file in write mode and then close it. For example, if your file myfile.dat contains:

"This is the original content"

Then you can simply write:

f = open('myfile.dat', 'w')
f.close()

This would erase all the content. Then you can write the new content to the file:

f = open('myfile.dat', 'w')
f.write('This is the new content!')
f.close()

User · Answer

You can do this   def deleteContent pfile       fn pfile name      pfile close       return open fn  w

User · Answer

What could be easier than something like this   import tempfile  for i in range 400       with tempfile TemporaryFile   as tf          for j in range 1000               tf write  Line    of file     format j i     That creates 400 temp files and writes 1000 lines to each temp file  It executes in less than 1 2 second on my unremarkable machine  Each temp file of the total is created and deleted as the context manager opens and closes in this case  It is fast  secure  and cross platform     Using tempfile is a lot better than trying to reinvent it

User · Answer

How to delete only the content of file in python   There is several ways of set the logical size of a file to 0  depending how you access that file   To empty an open file   def deleteContent pfile       pfile seek 0      pfile truncate       To empty a open file whose file descriptor is known   def deleteContent fd       os ftruncate fd  0      os lseek fd  0  os SEEK SET      To empty a closed file  whose name is known   def deleteContent fName       with open fName   w            pass        I have a temporary file with some content        I need to reuse that file   That being said  in the general case it is probably not efficient nor desirable to reuse a temporary file  Unless you have very specific needs  you should think about using tempfile TemporaryFile and a context manager to almost transparently create use delete your temporary files   import tempfile  with tempfile TemporaryFile   as temp         do whatever you want with  temp      lt -  tempfile  guarantees the file being both closed  and  deleted       on exit of the context manager

[python] How to delete only the content of file in python

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