On Aug 13, 7:50 am, Dave Angel <da...@ieee.org> wrote: > naaman wrote: > > On Aug 12, 1:35 pm, Dave Angel <da...@ieee.org> wrote: > > >> naaman wrote: > > >>> I'm writing my first Python script and > >>> I want to use fileinput to open a file in r+ mode. > >>> Tried fileinput.input(sys.argv[1:],"r+") but that didn't work. > >>> ANy ideas? > > >>> Need to find and overwrite a line in a file several times. > >>> I can do it using open and seek() etc. but was wondering if I can use > >>> fileinput. > > >>> thanks; > > >> I haven't used it, but check out the 'inplace' keyword parameter. > > >> DaveA > > > I've only Python for a week so I'm not sure what inplace does > > You should read the docs for it > (http://www.python.org/doc/2.6.2/library/fileinput.html ), > but it's not very clear to me either So I dug up an example on the web: > (ref: http://effbot.org/librarybook/fileinput.htm) > > import fileinput, sys > > for line in fileinput.input(inplace=1): > # /convert Windows/DOS text files to Unix files/ > if line[-2:] == "\r\n": > line = line[:-2] + "\n" > sys.stdout.write(line) > > The inplace argument tells it to create a new file with the same name as > the original (doing all the necessary nonsense with using a scratch > file, and renaming/deleting) for each file processed. Stdout is pointed > to that new version of the file. Notice that you have to explicitly > write everything you want to wind up in the file -- if a given line is > to remain unchanged, you just write "line" directly. > > If you're new to Python, I do not recommend trying to do open/seek to > update a text file in place, especially if you're in DOS. There are > lots of traps. the inplace method of fileinput avoids these by > implicitly creating temp files and handling the details for you, which > probably works great if you're dealing with text, in order. > > DaveA
Thanks Dave. I'll check that out -- http://mail.python.org/mailman/listinfo/python-list
