what is this #(sharp) files?

[Anonymous]

Hi, 

when I made some changes, I saw some files were made including '#' in the file's name.

what are these files?

I guess these are maybe for backup files, but why they made up to 5 files? not just only one.

Is there any problem , If I delete these files?

[one-of-the-robs]

Those are backup files, created every time you save. Eagle will, by default, generate up to nine of them.

It's useful to have more than one backup because sometimes you realise you've just saved it for the third time since making a really bad decision and you want to go back to before that.

If you're confident that your latest version is what you want, feel free to delete the backups.

[Anonymous]

Thanks @one-of-the-robs 

then how can I use this files, If I want to back ? 

can I open it in the Eagle?

Thanks again

[one-of-the-robs]

Eagle hides all the backup files and doesn't let you open them (or, at the very least, makes it hard). The easiest method is to rename the pair you want to look at in explorer. Beware that the numbers don't always coincide, as some changes only affect one of brd/sch and, if you save after such a change, only the affected file gets a backup. So check the time stamps to ensure you have a consistent pair. Then rename them something new, e.g. "MyProject.b#3"-->"MyProject-bak3.brd" and "MyProject.s#3"-->"MyProject-bak3.sch"

Then you can open that pair and check it's the one you want to revert to before renaming them to replace the latest.