ch58.htm

linux-unix130.linux.and.unix.ebooks130 linux and unix ebookslinuxLearning Linux - Collection of 12 E

<H3 ALIGN="CENTER"><A NAME="Heading7<FONT COLOR="#000077">Listing 58.3. The

/proc/ioports listing of IO ports on a Linux machine.</FONT><FONT COLOR="#0066FF"></FONT></H3>

<PRE><FONT COLOR="#0066FF">$ cat /proc/ioports

0000-001f : dma1

0020-003f : pic1

0040-005f : timer

0060-006f : keyboard

0080-009f : dma page reg

00a0-00bf : pic2

00c0-00df : dma2

00f0-00ff : npu

01f0-01f7 : ide0

0260-0263 : sbpcd

02f8-02ff : serial(auto)

0300-031f : NE2000

0340-035f : NE2000

0378-037f : lp

03c0-03df : vga+

03e8-03ef : serial(auto)

03f0-03f5 : floppy

03f6-03f6 : ide0

03f7-03f7 : floppy DIR

03f8-03ff : serial(auto)

</FONT></PRE>

<H3 ALIGN="CENTER"><A NAME="Heading8<FONT COLOR="#000077">Listing Process Information</FONT></H3>

<P>There is a large amount of information about a process. Let's look at the information

about the process ID 5454 by looking in the <TT>/proc/5454</TT> directory. The output

is shown in Listing 58.4.

<H3 ALIGN="CENTER"><A NAME="Heading9<FONT COLOR="#000077">Listing 58.4. The

directories under /proc/processID.</FONT><FONT COLOR="#0066FF"></FONT></H3>

<PRE><FONT COLOR="#0066FF">$ ls -l /proc/5454

total 0

-r--r--r--   1 khusain  users           0 Oct 18 08:52 cmdline

lrwx------   1 khusain  users          64 Oct 18 08:51 cwd -&gt; [0302]:132748

-r--------   1 khusain  users           0 Oct 18 08:52 environ

lrwx------   1 khusain  users          64 Oct 18 08:52 exe -&gt; [0302]:22524

dr-x------   1 khusain  users           0 Oct 18 08:52 fd

pr--r--r--   1 khusain  users           0 Oct 18 08:52 maps

-rw------    1 khusain  users           0 Oct 18 08:52 mem

lrwx------   1 khusain  users          64 Oct 18 08:52 root -&gt; [0302]:2

-r--r--r--   1 khusain  users           0 Oct 18 08:52 stat

-r--r--r--   1 khusain  users           0 Oct 18 08:52 statm

-r--r--r--   1 khusain  users           0 Oct 18 08:52 status

</FONT></PRE>

<P>The command line that invoked the file is shown in <TT>/proc/</TT>ID<TT>/cmdline</TT>.<TT>

</TT>Replace the ID with the process ID you are interested in. Get the ID from the

output <TT>ps ax</TT> command. All the arguments are strings separated by zero bytes.

These bytes have to be translated to new lines for each argument to be shown separately.

The way to see the output is to use this command:<FONT COLOR="#0066FF"></FONT>

<PRE><FONT COLOR="#0066FF">$ cat /proc/5454/cmdline | tr &quot;\000&quot; &quot;\n&quot;

vi

myfiles.txt$

</FONT></PRE>

<P>The working environment for a process can be seen via the <TT>/proc/environ</TT>

directory. As with the cmdline output, all zeros have to be translated to <TT>&quot;\n&quot;</TT>

for the output to be meaningful. If you do not do so, all the environment strings

will be gelled together in one long string on the output. The command will look a

bit like the one shown in Listing 58.5. (Your output will look different than what's

shown here.)

<H3 ALIGN="CENTER"><A NAME="Heading10<FONT COLOR="#000077">Listing 58.5. Listing

the working environment for a process.</FONT><FONT COLOR="#0066FF"></FONT></H3>

<PRE><FONT COLOR="#0066FF">$ cat /proc/5454/environ | tr &quot;\000&quot; &quot;\n&quot;

LESSOPEN=|lesspipe.sh %s

ignoreeof=10

HOSTNAME=www.ikra.com

LOGNAME=khusain

MINICOM=-c on

MAIL=/var/spool/mail/khusain

TERMCAP=vs|xterm|vs100|xterm terminal emulator (X Window System):am:bs:km:co#80:li#24:ct=\E[3k:ue=\E[m:is=\E[m\E[?1l\E&gt;:rs=\E[m

\E[?1l\E&gt;:eA=\E)0:as=^N:ae=^O:ac=aaffggjjkkllmmnnooqqssttuuvvwwxx:kI=\

E[2~:kD=:kP=\E[5~:kN=\E[6~:k1=\E[11~:k2=\E[12~:k3=\E[13~:k4=\E[14~:k5

=\E[15~:k6=\E[17~:k7=\E[18~:k8=\E[19~:k9=\E[20~:k0=\E[21~:F1=\E[23~:F2

=\E[24~:kh=\E[H:kH=\EOw:ks=:ke=:te=\E[2J\E[?47l\E8:ti=\E7\E[?47h:ms:pt

:xn:xo:it#8:RA=\E[?7l:SA=\E?7h:bl=^G:cr=^M:ta=^I:cm=\E[%i%d;%dH:le=^H:

up=\E[A:do=\E[B:nd=\E[C:LE=\E[%dD:RI=\E[%dC:UP=\E[%dA:DO=\E[%dB:ho=\E[

H:cl=\E[H\E[2J:ce=\E[K:cb=\E[1K:cd=\E[J:sf=\ED:sr=\EM:st=\EH:cs=\E[%i%

d;%dr:sc=\E7:rc=\E8:ic=\E[@:IC=\E[%d@:al=\E[L:AL=\E[%dL:dc=\E[P:DC=\E[

%dP:dl=\E[M:DL=\E[%dM:so=\E[7m:se=\E[m:us=\E[4m:mb=\E[5m:mh=\E[2m:md=\

E[1m:mr=\E[7m:me=\E[m:kb=:ku=\E[A:kd=\E[B:kr=\E[C:kl=\E[D:

TERM=xterm

HOSTTYPE=i386

PATH=/usr/local/bin:/bin:/usr/bin:/usr/X11/bin:/usr/games:.

HOME=/home/khusain

SHELL=/bin/bash

LS_OPTIONS=--8bit --color=tty -F -b -T 0

MANPATH=/usr/local/man:/usr/man/preformat:/usr/man:/usr/X11/man:/usr/openwin/man

LESS=-MM

DISPLAY=:0.0

OSTYPE=Linux

WINDOWID=8388621

OPENWINHOME=/usr/openwin

SHLVL=3

LS_COLORS=no=00:fi=00:di=01;34:ln=01;36:pi=40;33:so=01;35:bd=40;33;01:

d=40;33;01:ex=01;32:*.cmd=01;32:*.exe=01;32:*.com=01;32:*.btm=01;32:*.at=01;32:

*.tar=01;31:*.tgz=01;31:*.arj=01;31:*.taz=01;31:*.lzh=01;3:*.zip=01;31:*.z=01;

31:*.Z=01;31:*.gz=01;31:*.jpg=01;35:*.gif=01;35:*.bmp=01;35:*.xbm=01;35:*.xpm=

01;35:*.tif=01;35:=/usr/bin/vi$

</FONT></PRE>

<H3 ALIGN="CENTER"><A NAME="Heading11<FONT COLOR="#000077">Showing Memory Maps

for Processes</FONT></H3>

<P>Other good information about the process is where the sections of the process

are loaded in memory. This information is found in the <TT>/proc/mmaps</TT> directory.

Examining the directory for a process whose ID is 5454 gives the output shown in

Listing 58.6.

<H3 ALIGN="CENTER"><A NAME="Heading12<FONT COLOR="#000077">Listing 58.6. Showing

memory maps.</FONT><FONT COLOR="#0066FF"></FONT></H3>

<PRE><FONT COLOR="#0066FF">$ cat /proc/5454/maps

08048000-0805f000 r-xp 00000000 03:02 22524

0805f000-08061000 rw-p 00016000 03:02 22524

08061000-0806c000 rwxp 00000000 00:00 0

40000000-40005000 rwxp 00000000 03:02 46931

40005000-40006000 rw-p 00004000 03:02 46931

40006000-40007000 rw-p 00000000 00:00 0

40009000-4000b000 r-xp 00000000 03:02 87901

4000b000-4000c000 rw-p 00001000 03:02 87901

4000c000-40085000 r-xp 00000000 03:02 87903

40085000-4008b000 rw-p 00078000 03:02 87903

4008b000-400bd000 rw-p 00000000 00:00 0

bfffe000-c0000000 rwxp fffff000 00:00 0

</FONT></PRE>

<P>This is the format of each line in the output:<FONT COLOR="#0066FF"></FONT>

<PRE><FONT COLOR="#0066FF">address permissions offset major:minor inode

</FONT></PRE>

<P>The permissions are the same as those for a process--read, write, and execute.

The <TT>p</TT> stands for private section. If a section is shared, you should have

<TT>s</TT>. The offset is the offset within the file. The major and minor numbers

correspond to device names for this process, and the inode is the one corresponding

to the page.</P>

<P>One of the most common things you are likely to be concerned with while using

Linux is how much memory you're chewing up at the moment. To get a snapshot of the

current memory usage, you can use the <TT>free</TT> command or look at <TT>/proc/meminfo</TT>.

The output is simple and easy to understand, as shown in Listing 58.7.

<H3 ALIGN="CENTER"><A NAME="Heading13<FONT COLOR="#000077">Listing 58.7. Memory

information.</FONT><FONT COLOR="#0066FF"></FONT></H3>

<PRE><FONT COLOR="#0066FF">$ cat /proc/meminfo



        total:    used:    free:  shared: buffers:  cached:

Mem:  31670272 30707712   962560 15962112  1359872 13742080

Swap: 35090432   307200 34783232

MemTotal:     30928 kB

MemFree:        940 kB

MemShared:    15588 kB

Buffers:       1328 kB

Cached:       13420 kB

SwapTotal:    34268 kB

SwapFree:     33968 kB

</FONT></PRE>

<H3 ALIGN="CENTER"><A NAME="Heading14<FONT COLOR="#000077">Information on Disk

Usage</FONT></H3>

<P>Other interesting statistics for disk usage are available for those whose really

need to know how their system is working. Examining these statistics to see how your

system is fairing is a fairly reasonable way to look at the behavior of the system.

Look at the output from <TT>/proc/stat</TT> shown in Listing 58.8.

<H3 ALIGN="CENTER"><A NAME="Heading15<FONT COLOR="#000077">Listing 58.8. Statistics

on your system.</FONT><FONT COLOR="#0066FF"></FONT></H3>

<PRE><FONT COLOR="#0066FF">$ cat /proc/stat

cpu  7827918 0 697778 186968393

disk 505252 1 0 0

disk_rio 209050 1 0 0

disk_wio 296202 0 0 0

disk_rblk 525758 2 0 0

disk_wblk 592830 0 0 0

page 533561 699895

swap 17961 75

intr 200154670 195494089 644075 0 0 1201601 0 155 0 0 283570 240158

0 0 0 2291022 0

ctxt 11001290

btime 847886750

processes 23920

</FONT></PRE>

<P>The only time I really have used this output was to see how a very large sort

program was hitting the page count. The pages being swapped in and out of memory

are counted off in the display. The disk light never seemed to go off. The number

of page swaps jumped up a lot every time I ran the program when I had a mere 8MB

of RAM. After an upgrade to 32MB of RAM, and when I was not running the program in

an xterm, the number of pages did not jump up so dramatically. The CPU entry lists

the time spent in 1/100ths of seconds in user mode, system mode idling, and uptime.

The meanings of the cryptic numbers in the rest of the fields are listed in the man

pages.</P>

<P>Another item to look at is the <TT>/proc/uptime</TT> numbers, which list the total

number of seconds spent processing and those spent in idle state. These numbers might

not be as precise as you want. You should write your own benchmarking routines if

you want precise numbers. The output shown here from <TT>/proc/uptime</TT> is an

example:<FONT COLOR="#0066FF"></FONT>

<PRE><FONT COLOR="#0066FF">$ cat /proc/uptime

1954987.45 1869728.55

</FONT></PRE>

<P>The second item in the output is the idle time for the CPU. Note how the idle

time is almost 100 times the same number as the fourth number for the idle time in

the CPU field from the <TT>/proc/stat</TT> output. They don't match exactly, because

the time required between the typing of these two commands (or to collect this information)

is not zero.

<H3 ALIGN="CENTER"><A NAME="Heading16<FONT COLOR="#000077">Determining System

Specifications</FONT></H3>

<P>Through some judicious use of the information in <TT>/proc</TT>, a process can

determine the specifications for the curre



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