#-*- encoding: utf-8 -*-

def isonesplace(str):
    """判断字符串是否只有一个空格"""
    str = str.split(" ")
    return len(str)

def func(str):
    """将中间的空格替换成双等号=="""
    str = str.strip()
    while("==" not in str and isonesplace(str) != 2):
        str = str.replace("  ", " ")
    return str.replace(" ", "==")

def readfile(file):
    """返回file文件去除前两行和全部空格的字符串"""
    ## 读取depend.txt到list
    fr = open(file, 'r', encoding='utf-8')
    list = fr.readlines()
    fr.close()
    comment = ""
    num = 0
    ## 去除前两行和空格，将读取内容存入变量
    for i in list:
        num += 1
        if num > 2:
            row = i.strip()
            comment += row + "\n"
    # print(comment)
    return comment

def writefile(file, str):
    """将str字符串写入file文件"""
    comment = ""
    str = str.split("\n")
    num = 1
    for row in str:
        num += 1
        if (row is ""):
            break
        if(num < len(str)):
            comment += func(row) + "\n"
        else:
            comment += func(row)
    print(comment)
    # # 清空depend.txt
    # open(file, 'w').close()
    # 将comment重新写入depend.txt
    fw = open(file, 'w')
    with fw as f:
        f.write(comment)
    # fw.write(comment)
    fw.close()

if __name__ == "__main__":
    print("----------starting procedure---------")
    file = "depend.txt"
    str = readfile(file)
    writefile(file, str)
    print("----------termination routine--------")

执行脚本

python replace.py

@echo off
REM for /f %%i in ('cat depend.txt') do echo "pip download %%i"
for /f %%i in ('cat depend.txt') do echo %%i
for /f %%i in ('cat depend.txt') do pip download %%i
pause