python中提取包含特定字符的行、以指定字符开头、结尾的行

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")
sample=fp.readlines()

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

for i in sample:
    if "3" in i:
        file.write(i)
fp.close()
file.close()

2、运行程序，提取包含3的行

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")
sample=fp.readlines()

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

for i in sample:
    if "3" in i:
        file.write(i)
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
a 3 d
3 4 k
h f 3

3、提取以3开头的行

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")
sample=fp.readlines()

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

for i in sample:
    if i.startswith("3"):
        file.write(i)
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
3 4 k

4、提取以3结尾的行

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")
sample=fp.readlines()

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

for i in sample:
    if i.endswith("3\n"):
        file.write(i)
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
h f 3