On Jan 7, 2009, at 10:27 , Sheldon Givens wrote:
On Wed, Jan 7, 2009 at 7:48 AM, Ulrich Spoerlein
<uspoerl...@gmail.com>wrote:
On Wed, 07.01.2009 at 08:54:41 -0600, Sean C. Farley wrote:
On Wed, 7 Jan 2009, Ulrich Spoerlein wrote:
On Tue, 06.01.2009 at 11:52:39 -0800, Sheldon Givens wrote:
Hello everyone,
It occurs to me that FreeBSD ps lacks the ability to disable
header.
This seems like a really obvious feature, and I may have simply
missed it's existence (despite my relentlessly searching the man
page) but here is a small patch that sets the flag 'n' to disable
header output.
You've missed it, probably because it is non-obvious:
% ps -p 1 -o pid,cpu
PID CPU
1 0
% ps -p 1 -o pid= -o cpu=
1 0
%
Another way:
ps | tail +2
I'm not sure about the portability of tail +N, I seem to remember
that
AIX doesn't support it. Therefore I'd rather use
% ps | sed 1d
which is way more portable.
The three solutions above all work on my OpenSolaris machine (other
than cpu=, since the field is named pcpu). I don't currently have
access to HP-UX or AIX to test which do and do not work.
Cheers,
Ulrich Spoerlein
--
It is better to remain silent and be thought a fool,
than to speak, and remove all doubt.
Hello everybody,
Ulrich: I appreciate your solution, but it ends up being a pretty
ridiculous
command when you start desiring 6 or 7 fields.
Yes, which is why the sed/tail will do exactly what you want. UNIX was
built on the fact that small tools together will work together to do
something larger, no need to move all of the functionality into one
tool, that creates maintenance nightmares and just complicates
otherwise simple code.
Sean: Ulrich is right in saying that tail +val is unreliable when
coding for
portability.
And I guess I just feel like running a second command to do what
should be
possible to do with the first command (and is, on many platforms. ps
--no-headers on linux for example) is a problem and presents
opportunity for
continued refinement of the utility.
What other platforms besides Linux distributions? Just because they
exist by the hundreds does not mean they are different platforms.
xiste...@keyhole.network.lan:~$ ps -AflZ --no-headers
ps: illegal option -- no-headers
usage: ps [ -aAdefHlcjLPyZ ] [ -o format ] [ -t termlist ]
[ -u userlist ] [ -U userlist ] [ -G grouplist ]
[ -p proclist ] [ -g pgrplist ] [ -s sidlist ] [ -z
zonelist ] [-h lgrplist]
'format' is one or more of:
user ruser group rgroup uid ruid gid rgid pid ppid pgid sid
taskid ctid
pri opri pcpu pmem vsz rss osz nice class time etime stime
zone zoneid
f s c lwp nlwp psr tty addr wchan fname comm args projid
project pset lgrp
xiste...@keyhole.network.lan:~$ uname -a
SunOS Keyhole.network.lan 5.11 snv_101b i86pc i386 i86pc Solaris
I also read the entire man page for ps that is included and could not
find a single way to not include a header by using a simple flag, in
the man page they list the -o format as the only way to remove the
header.
HP-UX man page does not include an option either, besides the
aforementioned -o format option:
http://docs.hp.com/en/B2355-90690/ps.1.html
Same goes for IBM's AIX system:
http://publib16.boulder.ibm.com/doc_link/en_US/a_doc_lib/cmds/aixcmds4/ps.htm
Just because Linux has it does not mean it is an improvement that
should be imported. I think it is rather dumb idea really. What if in
the future we add a new field to the output of ps to give more
information (on Solaris for example, the -Z function lists what Zone
the command is running in (global, or non-global)), this changes the
amounts of fields that are listed. Now lets say some shell script that
was written a few years ago requires a certain option to be located in
field 7, and now that is moved over to field 8 it could cause all
kinds of issues, instead if the command is written out with -o pid=,
it is static and it won't change even if a new field is introduced to
ps, thereby decreasing future issues, and increasing portability since
you can select only the fields you require, making it more portable
(if using standardised fields) because now the field will always be in
the same place, no matter the platform.
Sheldon
Linuxisms that are bad should not be imported into FreeBSD. There is a
valid and documented way to suppress the header information using ps,
use it. If you are using this in a script of some sort, writing it out
once will save you a lot of headache and trouble later.
Bert JW Regeer
