systemv การใช้

• I should note that most Linux systems are moving away from SystemV-style init ( which is what's described above ) to systemd, which is much more sophisticated ( and concomitantly more complex ).
• The main difference between System V shared memory ( shmem ) and memory mapped I / O ( mmap ) is that SystemV shared memory is persistent : unless explicitly removed by a process, it is kept in memory and remains available until the system is shut down . mmap'd memory is not persistent between application executions ( unless it is backed by a file ).