lsof doesn't return files open by the same user

Question

Consider this simple scenario:

1. I open a text file ~/textfile.txt with vim in one terminal (tried with both edit and read-only modes).
2. In a different terminal, I run

/usr/sbin/lsof ~/textfile.txt

Get no results

Why?

Answer 1

When you use vi/vim to edit a file you aren't actually holding ~/<filename>open you are reading the file into ~/.<filename>.swp and then holding that temp file open.

If you run lsof ~/.<filename>.swp it will show you the information you are looking for.

NOTE: If you have multiple people editing the same file you will need to lsof ~/.<filename>.s* as each vi/vim session will create its own swap file but will name it differently