Writing Data to an output file in Python

Question

I am very new to scripting (this is my first one) and I'm trying to automate network tasks with python. I have built a script that takes a list of AP names from a text file and puts those ap names into the appropriate place within lines of configuration.

What I would really like is to have the final result saved to a file instead of printed to screen, and nothing I've tried yet has worked. Here's my script that prints to screen

f1=open("filename.txt","r")
Lines=f1.readlines()
for line in Lines:
line = line.strip()
    o1="ap name " + (line) + " lan port-id 1 enable"
    o2="ap name " + (line) + " lan port-id 2 enable"
    o3="ap name " + (line) + " lan port-id 3 enable"
    print(o1)
    print(o2)
    print(o3)

f1.close()

So, this works but then I'm having to copy paste it out of the print. I'd love to have it automatically export to a text file, but none of the things I've tried yet have worked. Thanks for the help!

Did you try finding the answer ? I am sure you will find the answer on Stack Overflow itself! For example Take a look into this answer .stackoverflow.com/questions/5214578/print-string-to-text-file — user5658788
– user5658788, Commented Dec 13, 2019 at 4:37
So I did f2=open("output.txt","w") as line 2 and instead of the print commands used f2.write(o1) and the document stayed blank — Smooshface
– Smooshface, Commented Dec 13, 2019 at 4:39
You can also simply redirect the output of running this script to a text file, for example python myscript.py > output.txt. — jarmod
– jarmod, Commented Dec 13, 2019 at 4:39
Do you really want to use the same line of input for all three ports, or do you have 3 lines of input, each of which should be assigned to a different port? — chepner
– chepner, Commented Dec 13, 2019 at 4:45

chepner · Accepted Answer · 2019-12-13 04:48:58Z

1

You just need to open a file for writing and tell print to use that file via the file argument, instead of sys.stdout.

with open("filename.txt", "r") as input, open("newfile", "w") as output:
    for line in input:
        line = line.strip()
        for i in [1,2,3]:
            print(f"ap name {line} lan port-id {i} enable", file=output)

edited Dec 13, 2019 at 4:48

answered Dec 13, 2019 at 4:42

chepner

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1 Comment

Smooshface Over a year ago

Thank you VERY much for the assistance, it works perfectly (as I'm sure you know). I have a follow-up question. So, I am very new to Python (installed it and looked at it for the first time last night and got to where I was) I understand everything I see in your solution except the f after print. What does the f do?

Sharan · Accepted Answer · 2019-12-13 04:45:05Z

0

The problem maybe with you opening in "w" mode as it erases and rewrites. Try "a" mode.

f1=open("filename.txt","r")
Lines=f1.readlines()
for line in Lines:
line = line.strip()
    o1="ap name " + (line) + " lan port-id 1 enable"
    o2="ap name " + (line) + " lan port-id 2 enable"
    o3="ap name " + (line) + " lan port-id 3 enable"
    print(o1)
    print(o2)
    print(o3)
    f2 = open("result.txt","a")
    f2.write("o1: %s\n" % o1)
    f2.write("o2: %s\n" % o2)
    f2.write("o3: %s\n" % o3)
    f2.close()

f1.close()

edited Dec 13, 2019 at 4:45

answered Dec 13, 2019 at 4:43

Sharan

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2 Comments

chepner Over a year ago

This is only going to write output based on the last line read from the input file.

Sharan Over a year ago

Yeah figured. Edited.

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