How do I copy code from my computer into x3270 emulator?

I'm using x3270 on Ubuntu 16.04. The zOS does not have a good editor and having to write a lot of code and fixing it is a pain.

I want to write code on my computer and copy it into x3270 window.

Is there a way to do this?

x3270 is a blocked based terminal interface and can be used. The approach would be to cut and paste code. Since you mentioned z/OS I assume you are using the TSO and ISPF. ISPF Edit (Option 2 by default) allows for a Text Edit Command (TE) so you can cut and paste larger blocks of text.

When you press enter you will see. You can then position the cursor and paste the text.

Sorry, I just had some assembler source handy but as you can see you can paste a large block of code. Its cumbersome though.

Personally, this is more of a stop gap measure for edits of limited size. There are better solutions.

I personally use VSCode on my local machine. There is a plugin for VSCode from an open source project called Zowe that provides a plugin for VSCode in the VSCode marketplace Visual code Extension for Zowe. This is extension allows for editing code from z/OS on your local system (I use a MacBook Pro) and facilitates the file transfer for you. This is my preferred option. It does require that z/OSMF is installed and configured. You'll need to check that setup on your system.

The final option is to use SFTP to transfer the file. SFTP will allow transfer to MVS and USS file systems and provides an ASCII to EBCDIC conversion as well.

SCP will only transfer files to a USS based filesystem and is an option if that fits your needs.