写入以读写模式打开的文件会改变结构

Question

我有一个文本文件，内容如下：

joe satriani is god 
steve vai is god
steve morse is god
steve lukather is god

我想用python写一个代码，它会改变文件行，如：

joe satriani is god ,absolutely man ..
steve vai is god,absolutely man ..
steve morse is god,absolutely man ..
steve lukather is god,absolutely man ..

我之前尝试过这样做一次，但没有得到想要的结果。所以，首先我尝试编写一个代码，它只会在第一行的末尾附加“absolutely man”。

所以，下面是我的代码：

jj = open('readwrite.txt', 'r+')

jj.seek(1)
n = jj.read()
print(" yiuiuiuoioio \n") #just for debugging
print(n)

f = n.split("\n" , n.count("\n")) #to see what I am getting
print(f)   #As it turns out read returns the whole content as a string
print(len(f[0])) # just for debugging
jj.seek(len(f[0])) #take it to the end of first line
posy = jj.tell() # to see if it actually takes it 
print(posy)
jj.write(" Absolutely ..man ")

但在执行代码时，我的文件更改为以下内容：

joe satriani is god Absolutely ..man d
steve morse is god
steve lukather is god

第二行被覆盖。如何在一行末尾附加到一个字符串？

我想以读取和追加模式打开文件，但它会覆盖现有文件。我不想从此文件中读取字符串并通过附加将其写入另一个文件。如何追加或更改文件的行？

有没有什么方法可以不用包？

Answer 1

如果你想写入同一个文件，这就是解决方案

  file_lines = []
    with open('test.txt', 'r') as file:
        for line in file.read().split('\n'):
            file_lines.append(line+ ", absolutely man ..")
    with open('test.txt', 'w') as file:
        for i in file_lines:
            file.write(i+'\n')

如果你想写入不同的文件，这是解决方案

with open('test.txt', 'r') as file:
    for line in file.read().split('\n'):
        with open('test2.txt', 'a') as second_file:
            second_file.write(line+ ", absolutely man ..\n")

Answer 2

given_str = 'absolutely man ..'
text = ''.join([x[:-1]+given_str+x[-1] for x in open('file.txt')])
with open('file.txt', 'w') as file:
    file.write(text)

Answer 3

试图用 seek 写一些东西。你只是重写而不是插入，所以你必须在写完文本后复制文件的末尾

jj = open('readwrite.txt', 'r+')
data = jj.read()

r_ptr = 0
w_ptr = 0
append_text = " Absolutely ..man \n"
len_append = len(append_text)
for line in data.split("\n"): #to see what I am getting
    r_ptr += len(line)+1
    w_ptr += len(line)
    jj.seek(w_ptr)
    jj.write(append_text+data[r_ptr:])
    w_ptr += len_append