With usage of 'grep' and 'find' commands write a shell script:

grepf <string> <dir1> [<dir2>...] [<--> [<grep additional options>...]] 

which calls 'grep' for all files and subdirectories from dir1 and others given
as arguments. 'grep' has to be called with options given after '--'.

Examples:

./grepf getpid /usr/include
./grepf getpid /usr/include ./lab3 -- -i