Create file without writing to it?

[mmkw43]

When my program runs for the first time I simply want to CREATE the file but not write anything to it. (filename.dat)

Later on in the program I will be writing and saving the data and that works fine but having a problem with "file doesn't exist" on the first run of the program and I can't figure this out.

Want to create the file the first time I run the program and then I suppose have it check (although don't really need that I guess) to see if it exists but WITHOUT altering the file in any way. -- thanks much for any help

[Laurens-wuyts]

Have a look here, maybe this solves your problem.

Laurens

[mmkw43]

Isn't there a simple make directory command? Been trying all afternoon to solve this.

[elParaguayo]

That's a different question to your original one.

For directories, there's this: https://docs.python.org/2/library/os.html#os.mkdir

Edit: and see this http://stackoverflow.com/questions/2731 ... -necessary

[JimmyN]

To create a new directory use mkdir
To create a zero byte file (empty) you can use the "touch" command. touch filename.dat
The "touch" command will also update the file modification time whether the file contains any data or not.

[mmkw43]

stupid me -- os.makedir ? -- i'll try that and just have it run once

[kusti8]

To create a new directory use mkdir
To create a zero byte file (empty) you can use the "touch" command. touch filename.dat
The "touch" command will also update the file modification time whether the file contains any data or not.

If you haven't noticed this post is in the Python section...

[gordon77]

When my program runs for the first time I simply want to CREATE the file but not write anything to it. (filename.dat)

Later on in the program I will be writing and saving the data and that works fine but having a problem with "file doesn't exist" on the first run of the program and I can't figure this out.

Want to create the file the first time I run the program and then I suppose have it check (although don't really need that I guess) to see if it exists but WITHOUT altering the file in any way. -- thanks much for any help

What are you trying to do when it says it doesn't exist, reading it?

Why not only read it if it exists?

Code: Select all

   if os.path.exists("filename.dat") == True:
      file = open("filename.dat","r")
      inputx = file.readline()  

[DougieLawson]

How about

Code: Select all

import os
def touch(path):
    with open(path, 'a'):
        os.utime(path, None)

[mmkw43]

I need to create the file (not folder -- so mkdir was my mistake) before I read it. I keep getting errors that the file doesn't exist (duh) when I try to read it. So I simply want to create an empty file myfile.dat when the program starts -- if it exists then it's ignored. Essentially creating the file(s) the first time the program is run.

I'm using pickle to read the file which I want to write in binary. But like I say, it needs to be created first in my python program.

This is working fine but can't get eml.dat to create --

Code: Select all

if not os.path.exists('/home/pi/eml.dat'):   #this line works fine
   what here ? (tried the suggestions -- no luck)

(later on in the program in a class I read the file as such  ---  einput = open('eml.dat', 'rb')

thanks

[gordon77]

Try...

open('filename.dat', 'w').close()

[DougieLawson]

Code: Select all

if not os.path.exists('/home/pi/eml.dat'):   #this line works fine
   what here ? (tried the suggestions -- no luck)

(later on in the program in a class I read the file as such  ---  einput = open('eml.dat', 'rb')

See above ^^^^

Code: Select all

path='/home/pi/eml.dat'
if not os.path.exists(path):   #this line works fine
    with open(path, 'a'):
        os.utime(path, None)

[mmkw43]

thanks friends.