The fourth column in the output of free is named shared. On most outputs I can see in internet, the shared memory is zero. But that's not the case on my computer:$ free -h          total        used        free      shared  buff/cache   availableMem:       7,7G        3,8G        1,1G        611M        2,8G        3,0GSwap:      3,8G          0B        3,8GHere is also an excerpt of the output of ps_mem.py: Private  +   Shared  =  RAM used   Program--------------------------------- 21.4 MiB +   1.0 MiB =  22.4 MiB   bash (9) 29.2 MiB +   5.3 MiB =  34.5 MiB   Xorg 35.9 MiB + 858.5 KiB =  36.7 MiB   tor 42.9 MiB +   9.6 MiB =  52.5 MiB   urxvt (16)121.0 MiB +  24.9 MiB = 145.8 MiB   okular (2)151.8 MiB +   2.8 MiB = 154.6 MiB   soffice.bin  3.7 GiB + 209.3 MiB =   4.0 GiB   chromium (39)---------------------------------                          4.6 GiB=================================What is the meaning of a shared memory?Main answer in the Question 14102 says: shared: a concept that no longer exists. It's left in the output for backward compatibility. Looks insufficient to me. A non-existent concept does not take 600+ MB of RAM.
What is the meaning of `shared` memory in the `free` shell command?
memory;ram