如题，OS情况和FREE运行情况如下，为什么没有-+ buffer/cache一行呢？另外available列和free列到底有啥区别，能否解释下？

[root@iZ94t0nyo72Z u03]# uname -a
Linux iZ94t0nyo72Z 3.10.0-1160.76.1.el7.x86_64 #1 SMP Wed Aug 10 16:21:17 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux
[root@iZ94t0nyo72Z u03]# free -wh
total used free shared buffers cache available
Mem: 15G 13G 825M 95M 84M 1.6G 2.1G
Swap: 8.0G 0B 8.0G