Get kernel information through command line and programatically

The primary command to get kernel information is uname. The uname command reports basic information about operating system and hardware kernel. For example “name -p” prints the processor type or “unknown”, if it cannot file one.
The “-r” option returns the kernel release version. To get full configuration for currently used kernel run the followung command: “cat /boot/config-$(uname -r)”.
The full information about current kernel may be gotten with “uname -a”:

Actually uname reads and parses content of /proc/version file, so the same information may be received by reading this file:

The alternative way to get the same information using sysctl (system control) command:

Now how to get the same kernel data programmatically, through . So sysctl API, file kernctl.cpp:

#include <stdio.h>
#include <sys/types.h>
#include <sys/sysctl.h>
int main(int n, char ** s)
{
  char szBuffer[255];
  size_t length = sizeof(szBuffer);
  int mib[4] = {0,0,0,0};
  size_t miblen = sizeof(mib)/sizeof(int);
  mib[0] = CTL_KERN;
  mib[1] = KERN_OSTYPE;
  int iError = sysctl(mib, 2, &szBuffer, &length, NULL, 0);
  if(iError == 0)
  {
    printf("OS type: %s\n", szBuffer);
  } else {
    printf("Cannot get OS type. Error: %d\n", iError);
  }
  mib[1] = KERN_OSRELEASE;
  length = sizeof(szBuffer);
  iError = sysctl(mib, 2, &szBuffer, &length, NULL, 0);
  if(iError == 0)
  {
    printf("OS release: %s\n", szBuffer);
  } else {
    printf("Cannot get OS release. Error: %d\n", iError);
  }
  mib[1] = KERN_VERSION;
  length = sizeof(szBuffer);
  iError = sysctl(mib, 2, &szBuffer, &length, NULL, 0);
  if(iError == 0)
  {
    printf("OS version and compile time: %s\n", szBuffer);
  } else {
    printf("Cannot get OS version. Error: %d\n", iError);
  }
  return 0;
}

Code testing result:

The sysctl command and API is specifically designed for kernel parameter tuning and may be used to only for reading kernel data and also for changing them.