Append some stuff into a file with only the last appended line reserved.

[Cameron Simpson]

On 01Sep2019 04:13, Hongyi Zhao <hongyi.zhao at gmail.com> wrote:
>I want to append some log of pycurl's downloading info to file, and I
>only want to reserve the last appended line when write.  How to do this?

Please describe this in more detail. Present a little pycurl output and 
then explain what portion of it should land in the log file.

Cheers,
Cameron Simpson <cs at cskk.id.au>