how to insert a new line at the end of a file (logfile)

[flaerpen]

Hi there!

I wonder how to add a new line at the end of my already existing file?

/flaerpen

[elbin]

Hi there!

I wonder how to add a new line at the end of my already existing file?

/flaerpen

>>> f=open('c:\\log.txt', 'r+')   ## open the file in reading and appending mode
>>> len(f.readlines())    ## initial check of number of lines
3
>>> f.seek(2)   ## go to the end of the file, not necessary here because we already read all of it, but in general...
>>> f.write('\n')   ## write a newline character
>>> f.seek(0)   ##  go to the beginning and check lines again...
>>> len(f.readlines())
4
>>> f.close()
 

Hope this is what you need. It is important to know where your pointer is in the file, or you can make a mess. Thus the seek function is useful.

[bvdet]

You also could open the file in append mode:

>>> f = open('your_file', 'a')
>>> f.write('\n')
>>> f.close()

[elbin]

You also could open the file in append mode:

>>> f = open('your_file', 'a')
>>> f.write('\n')
>>> f.close()

Well, yes, but to count the lines in the example I needed the 'r'. There may be another way, but I don't know it.

[bartonc]

Well, yes, but to count the lines in the example I needed the 'r'. There may be another way, but I don't know it.

bvdet has given the preferred answer. The simpler the better according to The Zen of Python.

[ghostdog74]

Well, yes, but to count the lines in the example I needed the 'r'. There may be another way, but I don't know it.

open("file","a").write("\n")
 

if you really need to count lines, use len(open(....).readlines()) first , before you do the appending.

[elbin]

bvdet has given the preferred answer. The simpler the better according to The Zen of Python.

Point taken. I just wanted to make it understandable, although I maybe forget that most people here know python better than me .

[bartonc]

Point taken. I just wanted to make it understandable, although I maybe forget that most people here know python better than me .

I hope you noticed that I said "preferred" instead of "right". The right answer is always what works best for the individual. But the Zen thing is a great guide.