查找包含特定字符串的行并将其添加到新文件中

Question

What I'm trying to do is look for the string " ESTABLISHED " within my text file. If it is found, it will print the entire line onto another txt file newestFile . Problem is, it only looks for the first line that contains the string " ESTABLISHED ", and saves it onto newestFile . I want to be able to copy and paste each line containing that string, not just one.

Here is my text

Proto Recv-Q Send-Q  Local Address          Foreign Address        (state)        rxbytes    txbytes
tcp4       0      0  192.168.1.6.50860      72.21.91.29.http       CLOSE_WAIT         892        691
tcp4       0      0  192.168.1.6.50858      www.v.dropbox.co.https ESTABLISHED      27671       7563
tcp4       0      0  192.168.1.6.50857      162.125.17.1.https     ESTABLISHED      17581       3642

and my code:

def script(file, newestFile):
    with open(file, 'r') as r:
        for line in r:
            if "ESTABLISHED" in line:
               with open(newestFile, "w") as output:
                  output.writelines(line)

Answer 1

with open(newestFile, "w") as output:
    output.writelines(line)

In each loop you are re-creating newestFile . Write mode ( w ) deletes the file and creates new one if there is one. So on each time it finds ESTABLISHED , your code deletes old one and creates new one.

Instead of w use append( a ) mode which will create new file if there isn't one and if there is a file, it will just append your values to the file.

with open(newestFile, "a") as output:
    output.writelines(line)

You might want to read more from docs on Reading and Writing Files