Full System Recursive Search for a String - Not Finishing

UNIX for Advanced & Expert Users
1

Using

grep -r -H "foobar" / > result

to give
all files that contain the string "foobar"

Half way , its waiting for some thing and does not end

Not Sure whats happening.
Any help is much appreciated

Thank you

2 
find / -type f -exec grep  -l foobar {} \;

You have probably hit some character special file that has a readlock on it. You don't want to read tty files anyway. This returns the names of file with the string 'foobar' in them.

3

So any way to avoid it hitting files with readlock on it?
There should be some way to successfully search the entire filesystem for a string.

Thanks Again