chdir("test") ## For eg:test can be directory where the files exist. 
unless (-d "BSD"){
    mkdir("BSD") or warn ("unable to create directory BSD");
}
unless (-d "SBSCSubsystem"){
    mkdir("SBSCSubsystem") or warn ("unable to create directory SBSCSubsystem");
}
unless (-d "MCBTSSubsytem"){
    mkdir("MCBTSSubsytem") or warn ("unable to create directory MCBTSSubsytem");
}