Q:

How to find files containing string?

I tried:
grep "$1-2400000" /media/linux/DATADISK/flashka/

It is running and doing nothing for a long time. Is there another way? It is not necessary to do that with the terminal. 

A:

You're missing a -r to match "all files" and should probably use single-quotes:
grep -r -l -F '$1-2400000' /media/linux/DATADISK/flashka/

With -l, grep will only show you filenames, not the match in the file.
-F greps for a fixed string, instead of a regex.
If your filenames contain spaces or other special characters, you may want to make use of find instead:
find /media/linux/DATADISK/flashka/ -type f -exec grep -l -F '$1-2400000' {} \;

