Can I get programmatic access to ulimit and sysctl.conf vars in Python?

Question

I'd like to verify that a large number of Linux hosts are set up correctly. Currently I can do this by grepping sysctl.conf and executing commands like ulimit:

[username@hostname ~]$ tail -2 /etc/sysctl.conf
fs.file-max = 65536
vm.max_map_count = 262144
[username@hostname ~]$ ulimit -u
4096

I'd like to write a script to gather all the following data:

• Maximum file descriptors
• Max threads
• Max map count

Sure, I can get this by automating my manual process, but is there a more programmatic way of getting this data in Python? I'd rather know what the OS reports the value as, and not what's in the config file - just in case there's a difference.

Answer 1

There are two locations you can get this information:

• for ulimit information, use the resource module; the process limit is the resource.RLIMIT_NPROC constant.

  import resource
  
  nproc_soft, nproc_hard = resource.getrlimit(resource.RLIMIT_NPROC)
  

• For reading current sysctl.conf values, read the /proc/sys filesystem. The options in sysctl.conf map one-on-one to paths in that system, just replace . with a path separator:

  # read the current setting for fs.file-max
  with open('/proc/sys/fs/file-max') as f:
      file_max = int(f.read())
  
  # thread count limit, kernel.threads-max
  with open('/proc/sys/kernel/threads-max') as f:
      threads_max = int(f.read())
  
  # map count limit, vm.max_map_count
  with open('/proc/sys/vm/max_map_count') as f:
      max_map_count = int(f.read())