Phpseclib：部分文件下载

Question

What is the best way (using phpseclib) to download a partial file. I have a log file where data is constantly appended. I would like to periodically connect to a remote server and download the latest chunk without downloading the whole file every time. Rsync would be perfect but its not installed on every server. I'm currently able to do it using a number of commands where I would record the last line number, than use tail (with last line number) and pipe it to a tmp file. SCP the tmp file to my local machine and than delete the tmp file.

However, this method is too complicated and intrusive (requires creating/deleting a file on a remote machine). Also, I can not install anything on the remote machine and they might be different (bsd, linux, solaris, etc).

Answer 1

The function definition for Net_SFTP::get is as follows:

function get($remote_file, $local_file = false, $offset = 0, $length = -1)

So maybe you could do $sftp->get('/path/to/file.log', false, $last_recorded_size) or something.