1、测试数据及脚本

root@DESKTOP-1N42TVH:/home/test# ls
test.py  test.txt
root@DESKTOP-1N42TVH:/home/test# cat test.txt
a 3 d
s 1 j
z c m
q e i
3 4 k
h f 3
root@DESKTOP-1N42TVH:/home/test# cat test.py
fp=open("test.txt","r")

file=open("result.txt","w")

for i in range(3):               ## 提取前三行
    file.write(fp.readline().strip())
    file.write("\n")

fp.close()
file.close()
root@DESKTOP-1N42TVH:/home/test# python3 test.py
root@DESKTOP-1N42TVH:/home/test# ls
result.txt  test.py  test.txt
root@DESKTOP-1N42TVH:/home/test# cat result.txt   ## 查看结果
a 3 d
s 1 j
z c m