Top - Frequently Asked Questions
This FAQ is broken out in to several topics.
"Where do I get the latest version of top?"
The latest version of top is now available at the site "ftp.groupsys.com" in
the directory "/pub/top". It is also available at "eecs.nwu.edu" in the
"Is there a web page for top?"
Not at this time, but I am planning one. When it is finally available, you
will be able to find it at "www.groupsys.com."
"Is there a mailing list for top?"
Currently there is a top developers mailing list that is used by beta
testers and other people who help me port the program to various machines.
I am planning a general mailing list for announcements and such, but it is
not yet available.
"How can I find out when all these things become available?"
Information about the web site and the mailing list will be made available
in future distributions of top. New distributions will be announced on the
appropriate Usenet newsgroups (including comp.sources.unix).
"Why does it take so long for a new version of top to go through the
beta test process?"
This is completely my fault. I have just not had the time recently to give
top the attention it deserves. I thank everyone for their patience, and I
hope that with the recent changes in the direction of my career that I can
spend more time on this.
"Top is not written in ANSI C. Do you ever plan to change that?"
Top predates ANSI C by about 5 years. Yeah, it'll get "fixed" eventually.
Probably in 3.5.
"Configure said that it saw /proc and is recommending that I install top
setuid root. Is there any way around this? Is it safe?"
There is no way around it. Complain to POSIX. Every effort has been made
to make top a secure setuid program. However, we cannot guarantee that
there are no security problems associated with this configuration. The
places where top is most vulnerable are the builtin kill and renice
commands. There is no internal top command that causes top to start a shell
as a subprocess. Some SVR4 systems may contain a bug that enables a user to
renice his own processes downward (to lower nice values that are more
favorable for the process). This problem has been fixed for the Solaris 2.x
modules, but may still exist in others. We will hopefully fix this up in
the next release.
"Why is Configure a c-shell script? I thought c-shell scripts were
They are. :-) I'll probably be rewriting the Configure script for the
"We just upgraded our operating system to a new version and top broke.
What should we do?"
Recompile it. Top is very sensitive to changes in internal kernel data
structures. It is not uncommon for a new version of the operating system to
include changes to kernel data structures.
"I just finished compiling top and it works fine for root, but when
I try to run it as a regular user it either complains about files
it can't open or it doesn't display all the information it should.
Did I do something wrong?"
Well, you're just not done. On many operating systems today, access to
many of the kernel memory devices and other system files is restricted to
either root or a particular group. The Configure script figures this out
(usually) and makes sure that the "intsall" rule in the Makefile will
install top so that anyone can run it successfully. However, you have to
*install* it first. Do this with the command "make install".
"Top is (not) displaying idle processes and I don't (do) want it to."
This default has only changed about a dozen times, and I finally got tired
of people whining about it. Go read the manual page for the current version
and pay special attention to the description of the "TOP" environment
"We have so much memory in our machine that the memory status display
(the fourth line) ends up being longer than 80 characters. This
completely messes up top's output. Is there a patch?"
Most modules have been changed to use new memory formatting functions which
will display large values in terms of megabytes instead of kilobytes. This
should fix all occurences of this problem. If you encounter a system where
this large memory display overflow is still occurring, please let me know
(send mail to ). Also note that newer versions of top can
use columns beyond 79, and understand window resizes. So you can always
make your window bigger.
"I tried to compile top with gcc and it doesn't work. I get
compilation errors in the include files, or I get an executable that
dumps core, or top displays incorrect numbers in some of the displays.
Gnu CC likes very much to use its own include files. Not being a gcc
expert, I can't explain why it does this. But I can tell you that if
you upgrade your operating system (say from Solaris 2.4 to Solaris
2.5) after installing gcc, then the include files that gcc uses will
be incorrect, especially those found in the "sys" directory. Your
choices are: (1) rebuild and reinstall the "standard" include files
for gcc (look for scripts in the distribution called "fixincludes" and
"fixing.svr4"), (2) compile machine.c with "CFLAGS=-I/usr/include"
then make the rest of the object files normally, or (3) use "cc".
Solaris 2.6 users should also consult FAQ #20.
"The cpu state percentages are all wrong, indicating that my machine is
using 95% system time when it is clearly idle. What's wrong?"
This can happen if you compiled with gcc using the wrong include files.
See the previous question.
"I tried compiling top under SunOS version 4.1.x and it got compile time
errors. Is there a patch?"
If you try compiling top in a "System V environment" under SunOS (that is,
/usr/5bin is before /usr/bin on your path) then the compilation may fail.
This is mostly due to the fact that top thinks its being compiled on a
System V machine when it really isn't. The only solution is to put /usr/bin
and /usr/ucb before /usr/5bin on your path and try again.
"When I run top on my SVR4-derived operating system, it displays all
the system information at the top but does not display any process
information (or only displayes process information for my own
processes). Yet when I run it as root, everything works fine."
Your system probably uses the pseudo file system "/proc", which is by
default only accessible by root. Top needs to be installed setuid root on
such systems if it is going to function correctly for normal users.
"Under Solaris 2, when I run top as root it only shows root processes,
or it only shows processes with a PID less than 1000. It refuses to
show anything else. What do I do?"
You probably compiled it with /usr/ucb/cc instead of the real C compiler.
/usr/ucb/cc is a cc front end that compiles programs in BSD source-level
compatability mode. You do not want that. Make sure that /usr/ucb is not
on your path and try compiling top again.
"Under Solaris 2, I compiled top using what I am sure is the correct
compiler but when I try to run it it complains about missing dynamic
libraries. What is wrong?"
Check to see if you have LD_LIBRARY_PATH defined in your shell. If you do,
make sure that /usr/ucblib is not on the path anywhere. Then try compiling
"Under Solaris 2, when I try to run top it complains that it can't open
the library "libucb.so.1". So I changed the LIBS line in m_sunos5.c
to include -R/usr/ucblib to make sure that the dynamic linker will look
there when top runs. I figured this was just an oversight. Was I
No, you were not right. As distributed, top requires NO alterations for
successful compilation and operations under Solaris 2.0, 2.1, 2.2, 2.3, 2.4,
and 2.5. You probably compiled top with /usr/ucb/cc instead of the real C
compiler. See FAQ #10 for more details.
"When I try to compile top under Solaris 2.6 using gcc I get compile
time errors. There appear to be problems with the include files,
such as 'u_rlimit has incomplete type' and/or 'u_saved_rlimit has
incomplete type'. I've already run fixinc.svr4 as per FAQ #13.
Why didn't that fix it?"
Only top versions 3.5 and later are compatible with Solaris 2.6. In
addition, there is a bug in gcc 2.7.2.x with the fixinc.svr4 script. The
patch is included in the top distribution as the file
"gcc-18.104.22.168-sol26.patch" and is also available from the top web site
("/top"). See the Solaris FAQ for more details
"When I try to run Configure, it complains about a syntax error."
Some versions of SCO's csh do not understand the syntax "$<". This breaks
Configure. You'll just have to hack around it for now: the Configure script
is going to be completely redone in the near future anyway.
"The load average and memory displays don't work right. Why?"
This is a known bug with the svr42 module. The problem has been traced down
to a potential bug in the "mem" driver. The author of the svr42 module is
working on a fix.
I'm still stuck. To whom do I report problems with top?"
The most common problems are caused by top's sensitivity to internal kernel
data structures. So make sure that you are using the right include files,
and make sure that you test out top on the same machine where you compiled
it. Sun's BSD Source Compatability Mode is also a common culprit. Make
sure you aren't using either /usr/ucb/cc or any of the libraries in
/usr/ucblib. Finally, make sure you are using the correct module. If there
does not appear to be one appropriate for your computer, then top probably
will not work on your system.
If after reading all of this file and checking everything you can you are
still stuck, then send mail to "email@example.com". I will answer your mail
when I have time. Please bear with me in that regard! If it looks like the
problem is machine-specific, I will forward the report along to the module's
author. If you would like to converse directly with the module author, the
authors' names are listed at the beginning of the module .c file in the
Last updated: Tue Nov 18 22:48:26 EST 1997