Update a process name in linux to change how it shows up in top and lsof

linux_proc_name.rb

#
# Eric Lindvall <eric@5stops.com>
# 
# Update the process name for the process you're running in.
#
# This will allow top, lsof, and killall to see the process as the
# name you specify.
#
# Just use:
#
#     LinuxProcName.set_proc_name('deeplinux')
#
# To change the way the process name looks in ps, use:
#
#     $0 = "deeplinux"
#

require 'ffi'

module LinuxProcName
  # Set process name
  PR_SET_NAME = 15

  module LibC
    extend FFI::Library
    ffi_lib FFI::Library::LIBC

    begin
      attach_function :prctl, [ :ulong, :ulong, :ulong, :ulong ], :int
    rescue FFI::NotFoundError
      # We couldn't find the method
    end
  end

  def self.set_proc_name(name)
    return false unless LibC.respond_to?(:prctl)

    # The name can be up to 16 bytes long, and should be null-terminated if
    # it contains fewer bytes.
    name = name.slice(0, 16)
    ptr = FFI::MemoryPointer.from_string(name)
    LibC.prctl(PR_SET_NAME, ptr.address, 0, 0)
  ensure
    ptr.free if ptr
  end
end