How to check in a folder all files which doesnt have the specifc string?

I have a folder with 100s of dat files, with delimiter "|", in some files they didn't provide this delimiter. how to automatically check those list of files in a folder which doesnt have a delimiter or string this way "|" is it possible?

Thank you very much for the helpful info.

Yes. You can generate a list of file with

fgrep -L '|' *.dat 

This works with the Linux versions, not other UNIX OSes.

You would have gotten a better answer if you gave us your exact Os and the shell you use.
fgrep turns "off" the use of regular expressions. It is the same as grep -F Someone else on UNIX.com is sure to note that fgrep is deprecated, I use it for clarity here.

How about grep -lv '[|]' *.dat

If this is to be part of a script that will do different things depending on whether or not a pipe is found, you might want to add a -q to the command line when you no longer need to see its active. Your if statement can check the status code.