1. Accept option x or x and b
   eg: sh script -x <arg> (or)             ;will execute function a defined in script
       sh script -x <arg> -b               ;will execute the functions a and b

2. Accept option m or m and b
   eg: sh script -m <arg> (or)     ;execute function c
       sh script -m <arg1> -b   ;should execute function for c and b

3. Option both x and m should not be passed together.
   This will print usage(how to use the input options) function.

4. Option v. This should not be passed with any other option.
   eg: sh script -v <arg>  ; executs the function for v

while ((ch = getopt(argc, argv, "HLPRafilnprsvx")) != -1)
        switch (ch) {
        case 'H':
                Hflag = 1;
                Lflag = 0;
                break;
        case 'L':
                Lflag = 1;
                Hflag = 0;
                break;
        ...
        case 'l':
                lflag = 1;
                break;
        ...
        case 's':
                sflag = 1;
                break;
        case 'v':
                vflag = 1;
                break;
        case 'x':
                fts_options |= FTS_XDEV;
                break;
        default:
                usage();
                break;
        }

if (lflag && sflag)
        errx(1, "the -l and -s options may not be specified together");