How can I simulate a “locked” file (one which has a write lock)

Question

I am trying to debug a problem where users occasionally have locked files which they try to open. The code appears to have correct exception handling but users are still report

Answer 1

I am using this command prompt

type yourfile.txt | more

to insert inside yourfile.txt a very long text of "few pages" and want to pipe via | more to batch the insertion. However the file seems to lock, any reason why?