Read and Write Large Files - Mikrotik Script
How To Read and Write Large Files

Many users requested ability to work with files. Now you can do it without limitations.

Create and write to file:

:global newContent "new file content\r\nanother line\r\n";
[/lua "local f=assert(io.open('/test.txt', 'w+')); f:write(newContent); f:close()" ];

Read file content to variable:

:global cnt ""
[/lua "local f=assert(io.open('/test.txt', 'r')); cnt=f:read('*all'); f:close()" ];
:put $cnt