linux basic sys calls

system calls

    memset() : This function fills the first n bytes of the memory area pointed to by s with the constant byte c.
    fopen() : This function opens the file whose name is the string pointed to by its first argument and associates a stream with it.
    getcwd() : This function return a null-terminated string containing an absolute pathname that is the current working directory of the calling process
    getuid() : This function returns the real user ID of the calling process
    snprintf() : This function produces output according to a format and writes the output to a buffer.
    fwrite() : This function is used to write data to a stream
    fflush() : This function forces a write of all user space buffered data on to a particular stream
    fclose() : This function flushes the associated stream and closes the underlying file descriptor.
    system() : This function executes a command
    sleep() : This function makes the calling process sleep until specified seconds have elapsed or a signal arrives which is not ignored.
    opendir() : This function opens a directory stream
    readdir() : This function reads the directory which is opened as a stream
    atoi() : This function converts ascii argument to integer.