there is a specific file in which there is a word "Dictotia".I don't know where the file is present and i want to find the file in which the word is present.It is something like homework by my teacher.

Hi there

Something like homework, or it is homework? Well, it's commendable that you did mention that, but did your teacher happen to give you any idea where to look for how to do this? Have you looked at the man page for grep? Looks like you're posting from Windows, so.. What Linux does this refer to (that you're working on), or are you doing this on Windows or Cygwin? It may make a difference at some point, but from your terminal, type:
and examine the -R option and -l option (that's a lowercase L). Grep syntax (there's a hint in there) is typically:

grep <options> <regex or word> file/path/*


Note that if the filesystem is very large, you may run into problems with resources or memory. If you need further help, show us what command(s) you're trying, and what's not working about it.

In addition to the above information, if you are searching the entire system you may also run into permission issues.