Resolved: How to save only 5 lines in file with python code?

In this post, we will see how to resolve How to save only 5 lines in file with python code?

Question:

def saveKey(key):
     try:
         f=open("/etc/savekeys","w")
         f.write(str(key.replace("|", "")))
         f.close()
     except:
         pass

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Best Answer:

• Age in the file is determined from the top down. The first line is the oldest, and the last line is the newest. Any new lines are always placed at the end of the file.
• You’re only writing one line at a time.
• No threading or multiple processes are involved in this.

• Open the file to get all lines.
• Add your line.
• If the number of lines exceeds your cap, then remove the first line.
• Write all lines out.

def save_key(key, max_lines=5):
    lines = []
    with open("file", "r") as f:
        lines = f.readlines()

    lines.append(key)

    lines = lines[-max_lines:]

    with open("file", "w") as f:
        f.writelines(lines)

If you have better answer, please add a comment about this, thank you!

Source: Stackoverflow.com