1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
|
@node White Paper, Reference Manual, About, Top
@chapter LibGTop White Paper
@menu
* Introduction::
@end menu
@node Introduction, , White Paper, White Paper
@section Introduction
Many modern UNIX systems like Solaris, BSD or Digitial Unix only allow
priviledged processes to read information like CPU and Memory Usage or
information about running processes.
@itemize @bullet
@item
BSD, for instance, doesn't have any other way to get those data than reading
directly from @file{/dev/kmem} and you need to be in the @code{kmem} group to
be able to read this.
@item
Other systems, like Digital Unix, allow all users to get things like CPU and
Memory statistics, but only root may read information about any process other
than the current one (you may not even get information about your own processes
if you're not root).
@item
Linux has a very nice @file{/proc} filesystem, but reading and parsing
@file{/proc} is very slow and inefficient.
@item
Solaris is a bit better, but you still need to be in the @code{sys} group or
even root to get some data.
@end itemize
Because of this system utilities like @code{ps}, @code{uptime} or @code{top}
often are setgid kmem or setuid root. Usually, they're also very specific to
the system they're written for and not easily portable to other systems without
a lot of work.
|
