Shell Programming and Scripting

grep [-n] <parameters> <file>
grep [-v] <parameters> <file>
grep [-y] <parameters> <file>
grep [-i] <parameters> <file>
grep [-w] <parameters> <file>
grep [-f file] <parameters> <file>

#!/bin/sh
echo "

----------------------------------------------------------------------
"
while true;do
echo -n "           << Grep Simulation Script >>

----------------------------------------------------------------------

                   1.(n) Grep -n
                   2.(v) Grep -v
                   3.(y) Grep -y
                   4.(i) Grep -i 
                   5.(w) Grep -w
                   6.(f) Grep -f
                   7. (E)xit

             Doste epilogi gia prosomoiosi:   (Give your choise for sim)"
read epilogi
case $epilogi in
1|n|N)./grep-n;;
2|v|V)./grep-v;;
3|y|Y)./grep-y;;
4|i|I)./grep-i;;
5|w|W)./grep-w;;
6|f|F)./grep-f;;
7|e|E) exit 0;; 
*)echo " 

       !!!<< Dosate lathos epilogi, dokimaste ksana(wrong choise, try again, >>!!!
----------------------------------------------------------------------
";;
esac
done

grep `example` file 

in sed is : 

sed -n `/example/p` file

gawk '
function menu(){
        printf "\n<< Grep Simulation Script >>\n"
        print "------------------------------"
        print "1.(n) Grep -n"
        print "2.(v) Grep -v"
        print "3.(i) Grep -i"
        print "4.(w) Grep -w"
        print "5.(f) Grep -f"
        print "6. (E)xit"

}
function exists(file,      dummy, ret) {
   ret=0;
   if ( (getline dummy < file) >=0 ) {ret = 1; close(file)};
   return ret;
}

function grep(filename,text,linenum,invert,whole ){
   if ( exists(filename) ){
        linecount=0
        while ( (getline line < filename ) > 0 ) {
            linecount++
            if ( invert && line !~ text){
                print line
            }else if ( whole ){
                z=split(line, L, " ")
                for(j=1;j<=z;j++){
                    gsub(/^ +| +$/,"",L[i])
                    if ( L[j] == text ){
                        print line
                    }
                }
            } else if ( line ~ text) {
                if ( linenum )
                    print linecount": "line
                else { print line }
            }
        }
   }else{
        print "File: "filename" does not exists"
        return 1
   }

}
BEGIN{
    while(1){
        IGNORECASE=0
        linenum=0
        invert=0
        menu()
        printf "Your choice: "
        getline choice <"-"
        if ( choice == 1 ){
            linenum=1
        }else if ( choice == 2){
            invert=1
        }else if ( choice == 3 ){
            IGNORECASE=1
        }else if ( choice == 4){
            whole=1
        }else if ( choice == 5) {
            print "Not implemented"
            continue
        }else if ( choice == 6) {
            print "Exiting...."
            exit
        }
        printf "Enter text to search: "
        getline text <"-"
        printf "Enter filename: "
        getline file < "-"
        grep(file,text,linenum,invert,whole)
    }
}'