Python-如何在文本/ conf文件的每一行末尾添加空格字符串（''）

Question

I have a config file that i would like to add a space (' ') to the end of every line in the file

File example:

#xxx configuration
IPaddr = 1.1.1.1<add a space here>
host = a.b.c.d<add a space here>
usrname = aaa<add a space here>
dbSID = xxx<add a space here>

i already have the number of lines in the file (using len) so i know how much time to repeat the loop of adding the space string. i also know how to open a file for reading and writing.

Thank you all.

Answer 1

You can use fileinput with inplace=True to update the original file:

import fileinput
import sys
for line in fileinput.input("in.txt",inplace=True):
    sys.stdout.write("{} \n".format(line.rstrip()))

Or use a tempfile.NamedTemporaryFile with shutil.move :

from tempfile import NamedTemporaryFile
from shutil import move

with open("in.txt") as f, NamedTemporaryFile("w",dir=".", delete=False) as temp:   
    for line in f:
       temp.write("{} \n".format(line.rstrip()))
move(temp.name,"in.txt")

Answer 2

You don't need to know the length of your file. In python files are iterators that yield lines. No need for c-style for-loops.

So something like this should work for you (python3 or from __future__ import print_function ):

with open('file.in') as infile, open('file.out', 'w') as outfile:
    for line in infile:
        print(line.strip() + ' ', file=outfile)

Answer 3

You can do this (on the same file) by opening the file for reading with "r" flag,

Then, for each row in the file, add a space before the new line character ("\\n"),

And finally, open the file for writing with "w' flag, and write the updated content with writelines() function.

with open('config.txt', 'r') as source:
    lines = [line.replace("\n"," \n") for line in source.readlines()]
with open("config.txt", "w") as target:
    target.writelines(lines)

Please note, I assume that the file is a UNIX file so it does not contain "\\r" character before the "\\n", if it is not the case, line number 2 should be:

    lines = [line.replace("\r\n"," \r\n") for line in source.readlines()]