superuser

Files from which vmstat information come from

I would very much like to know the names and locations of the files from which vmstat command information comes from in Linux OS.

Solution

  • User space tools reporting statistics likely get them from the kernel through procfs/sysfs file systems. As most of them are open sources, it is easy to read the source code. For example, a way to get the package name it comes from is to display the version:

    $ vmstat --version
vmstat from procps-ng 3.3.16

    From the preceding, you know that you can grab the source code from procps-ng package.

    And as said in the comments by Stark, you can spy the execution of vmstat with strace tool and you will see which files are opened to get the information:

    $ strace vmstat
[...]
openat(AT_FDCWD, "/proc/meminfo", O_RDONLY) = 3
[...]
openat(AT_FDCWD, "/proc/stat", O_RDONLY) = 4
[...]
openat(AT_FDCWD, "/proc/vmstat", O_RDONLY) = 5
[...]