How do I transfer a file from one directory to another using Java SFTP Library JSch?

Question

I need to program a file transfer using JSch library. I have a simple directory with two folders -

In the SFTP_1 folder, I have a bitmap image

Answer 1

A core SFTP protocol does not support duplicating remote files.

There's a draft of copy-file extension to the protocol, but that's supported by only few SFTP servers (ProFTPD/mod_sftp and Bitvise SFTP server for example).

It's definitely not supported by the most widespread OpenSSH SFTP server.

And it's also not supported by the JSch library.

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See also my answer to How can I copy/duplicate a file to another directory using SFTP?

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So actually using the cp shell command over an "exec" channel (ChannelExec) is unfortunately the best available approach (assuming you connect to a *nix server and you have a shell access).

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If you do not have a shell access, then your only option is indeed to download the file to a local temporary folder and upload it back to the new location (or use streams, to avoid a temporary file). This is what the accepted answer by @Edwin Buck shows.