top.1

linux下获取一些环境信息的代码

.br
The \*(CW is the window associated with the \*(SA and the window to which
task related commands are always directed.
Since in \*(AM you can toggle the \*(TD \*F, some commands might be
restricted for the \*(CW.

A further complication arises when you have toggled the first \*(SA
line \*F.
With the loss of the window name (the 'l' toggled line), you'll not easily
know what window is the \*(CW.

.\" ......................................................................
.SS 4b. COMMANDS for Windows
.TP 7
\ \ \'\fB-\fR\' and \'\fB_\fR\' :\fIShow/Hide_Window(s)_toggles\fR
The '-' key turns the \*(CW's \*(TD \*O and \*F.
When \*O, that \*(TA will show a minimum of the columns header you've
established with the 'f' and 'o' commands.
It will also reflect any other \*(TA options/toggles you've applied yielding
zero or more tasks.

The '_' key does the same for all \*(TDs.
In other words, it switches between the currently visible \*(TD(s) and any
\*(TD(s) you had toggled \*F.
If all 4 \*(TDs are currently visible, this \*(CI will leave the \*(SA
as the only display element.

.TP 7
*\ \'\fB=\fR\' and \'\fB+\fR\' :\fIEqualize_(re-balance)_Window(s)\fR
The '=' key forces the \*(CW's \*(TD to be visible.
It also reverses any 'i' (idle tasks) and 'n' (max tasks) commands that might
be active.

The '+' key does the same for all windows.
The four \*(TDs will reappear, evenly balanced.
They will also have retained any customizations you had previously applied,
except for the 'i' (idle tasks) and 'n' (max tasks) commands.

.TP 7
*\ \'\fBA\fR\' :\fIAlternate_Display_Mode_toggle\fR
This command will switch between \*(FM and \*(AM.

The first time you issue this command, all four \*(TDs will be shown.
Thereafter when you switch modes, you will see only the \*(TD(s) you've
chosen to make visible.

.TP 7
*\ \'\fBa\fR\' and \'\fBw\fR\' :\fINext_Window_Forward/Backward\fR
This will change the \*(CW, which in turn changes the window to which
commands are directed.
These keys act in a circular fashion so you can reach any desired \*(CW
using either key.

Assuming the window name is visible (you have not toggled 'l' \*F),
whenever the \*(CW name loses its emphasis/color, that's a reminder
the \*(TD is \*F and many commands will be restricted.

.TP 7
*\ \'\fBG\fR\' :\fIChoose_Another_Window/Field_Group\fR
You will be prompted to enter a number between 1 and 4 designating the
window/field group which should be made the \*(CW.

In \*(FM, this command is necessary to alter the \*(CW.
In \*(AM, it is simply a less convenient alternative to the 'a' and 'w'
commands.

.TP 7
\ \ \'\fBg\fR\' :\fIChange_Window/Field_Group_Name\fR
You will be prompted for a new name to be applied to the \*(CW.
It does not require that the window name be visible
(the 'l' toggle to be \*O).

.IP "*" 3
The \*(CIs shown with an \*(AS have use beyond \*(AM.
    \'=', 'A', 'G'  are always available
    \'a', 'w'       act the same when color mapping


.\" ----------------------------------------------------------------------
.SH 5. FILES
.\" ----------------------------------------------------------------------
.\" ......................................................................
.SS 5a. SYSTEM Configuration File
The presence of this file will influence which version of the 'help' screen
is shown to an ordinary user.
More importantly, it will limit what ordinary users are allowed
to do when \*(Me is running.
They will not be able to issue the following commands.
   k         Kill a task
   r         Renice a task
   d or s    Change delay/sleep interval

The system \*(CF is\fB not\fR created by \*(Me.
Rather, you create this file manually and place it in the \fI/etc\fR
directory.
Its name must be 'toprc' and must have no leading '.' (period).
It must have only two lines.

Here is an example of the contents of\fI /etc/toprc\fR:
   s         # line 1: 'secure' mode switch
   5.0       # line 2: 'delay'\ \ interval in seconds

.\" ......................................................................
.SS 5b. PERSONAL Configuration File
This file is written as '$HOME/.your-name-4-top' + 'rc'.
Use the 'W' \*(CI to create it or update it.

Here is the general layout:
   global    # line 1: the program name/alias notation
     "       # line 2: id,altscr,irixps,delay,curwin
   per ea    # line a: winname,fieldscur
   window    # line b: winflags,sortindx,maxtasks
     "       # line c: summclr,msgsclr,headclr,taskclr

If the $HOME variable is not present, \*(Me will try to write the
personal \*(CF to the current directory, subject to permissions.


.\" ----------------------------------------------------------------------
.SH 6. STUPID TRICKS Sampler
.\" ----------------------------------------------------------------------
Many of these 'tricks' work best when you give \*(Me a scheduling boost.
So plan on starting him with a nice value of -10, assuming you've got
the authority.

.\" ......................................................................
.SS 6a. Kernel Magic
.\" sorry, just can't help it -- don't ya love the sound of this?
For these stupid tricks, \*(Me needs \*(FM.
.\" ( apparently AM static was a potential concern )

.New
The user interface, through prompts and help, intentionally implies
that the delay interval is limited to tenths of a second.
However, you're free to set any desired delay.
If you want to see Linux at his scheduling best, try a delay of .09
seconds or less.

For this experiment, under x-windows open an xterm and maximize it.
Then do the following:
  . provide a scheduling boost and tiny delay via:
      nice -n -10 top -d.09
  . keep sorted column highlighting \*F to minimize
    path length
  . turn \*O reverse row highlighting for emphasis
  . try various sort columns (TIME/MEM work well),
    and normal or reverse sorts to bring the most
    active processes into view

What you'll see is a very busy Linux doing what he's always done for you,
but there was no program available to illustrate this.

.New
Under an xterm using 'white-on-black' colors, try setting \*(Me's task color
to black and be sure that task highlighting is set to bold, not reverse.
Then set the delay interval to around .3 seconds.

After bringing the most active processes into view, what you'll see are
the ghostly images of just the currently running tasks.

.New
Delete the existing rcfile, or create a new symlink.
Start this new version then type 'T' (a secret key, \*(Xt 3c. TASK Area
Commands, Sorting) followed by 'W' and 'q'.
Finally, restart the program with -d0 (zero delay).

Your display will be refreshed at three times the rate of the former \*(Me,
a 300% speed advantage.
As \*(Me climbs the TIME ladder, be as patient as you can while speculating
on whether or not \*(Me will ever reach the \*(Me.

.\" ......................................................................
.SS 6b. Bouncing Windows
For these stupid tricks, \*(Me needs \*(AM.

.New
With 3 or 4 \*(TDs visible, pick any window other than the last
and turn idle processes \*F.
Depending on where you applied 'i', sometimes several \*(TDs are bouncing and
sometimes it's like an accordion, as \*(Me tries his best to allocate space.

.New
Set each window's summary lines differently: one with no memory; another with
no states; maybe one with nothing at all, just the message line.
Then hold down 'a' or 'w' and watch a variation on bouncing windows \*(EM
hopping windows.

.New
Display all 4 windows and for each, in turn, set idle processes to \*F.
You've just entered the "extreme bounce" zone.

.\" ......................................................................
.SS 6c. The Big Bird Window
This stupid trick also requires \*(AM.

.New
Display all 4 windows and make sure that 1:Def is the \*(CW.
Then, keep increasing window size until the all the other \*(TDs
are "pushed out of the nest".

When they've all been displaced, toggle between all visible/invisible windows.
Then ponder this:
.br
   is \*(Me fibbing or telling honestly your imposed truth?


.\" ----------------------------------------------------------------------
.SH 7. BUGS
.\" ----------------------------------------------------------------------
Send bug reports to:
   Albert D\. Cahalan, <[e-mail]>


.\" ----------------------------------------------------------------------
.SH 8. HISTORY Former top
.\" ----------------------------------------------------------------------
The original top was written by Roger Binns,
based on Branko Lankester's <[e-mail]> ps program.

Robert Nation <[e-mail]>
adapted it for the proc file system.

Helmut Geyer <[e-mail]>
added support for configurable fields.

Plus many other individuals contributed over the years.


.\" ----------------------------------------------------------------------
.SH 9. AUTHOR
.\" ----------------------------------------------------------------------
This entirely new and enhanced replacement was written by:
   Jim / James C. Warner, <[e-mail]>
.ig
   ( as a means to learn Linux, can you believe it? )
   ( & he accidentally learned a little groff, too! )
..

With invaluable help from:
   Albert D\. Cahalan, <[e-mail]>
   Craig Small, <[e-mail]>

.ig
.rj 2
.B -*-\fR few though they are, some yet believe\fB -*-\fR
.B -*-\~\~\~\~\~\~\~\fRin-the-\fBart\fR-of-programming\~\~\~\~\~\~\~\fB-*-\fR
..

.\" ----------------------------------------------------------------------
.SH 10. SEE ALSO
.\" ----------------------------------------------------------------------
.BR free (1),
.BR ps (1),
.BR uptime (1),
.BR atop (1),
.BR slabtop (1),
.BR vmstat (8),
.BR w (1).


.\" ----------------------------------------------------------------------
.ig
.rj 1
\-*-
.PD
.in -3
Copyright (c) 2002 \*(EM JC Warner & Associates, Ltd.

Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.1 or
any later version published by the Free Software Foundation;
with no Front-Cover Texts, no Back-Cover Texts, and with the following
Invariant Sections and any sub-sections therein:
.na
.hy 0
.in +3
STUPID\ TRICKS\ Sampler;
.br
AUTHOR
.in
A copy of the license is included in the section entitled
\(dqGNU Free Documentation License\(dq.
..
.
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.ig
.\" ----------------------------------------------------------------------
.SH GNU Free Documentation License
Version 1.1, March 2000

Copyright (C) 2000  Free Software Foundation, Inc.
    59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.

.SS 0. PREAMBLE
The purpose of this License is to make a manual, textbook, or other
written document "free" in the sense of freedom: to assure everyone
the effective freedom to copy and redistribute it, with or without
modifying it, either commercially or noncommercially.  Secondarily,
this License preserves for the author and publisher a way to get
credit for their work, while not being considered responsible for
modifications made by others.

This License is a kind of "copyleft", which means that derivative
works of the document must themselves be free in the same sense.  It
complements the GNU General Public License, which is a copyleft
license designed for free software.

We have designed this License in order to use it for manuals for free
software, because free software needs free documentation: a free
program should come with manuals providing the same freedoms that the
software does.  But this License is not limited to software manuals;
it can be used for any textual work, regardless of subject matter or
whether it is published as a printed book.  We recommend this License
principally for works whose purpose is instruction or reference.

.SS 1. APPLICABILITY AND DEFINITIONS
This License applies to any manual or other work that contains a
notice placed by the copyright holder saying it can be distributed
under the terms of this License.  The "Document", below, refers to any