Desvio Condicional em Shell Script

Para efetuar teste condicionais, o shell script possui operadores de verificação como (maior/menor/menor que/igual/ etc …) veja abaixo os exemplos :

if [ condição ]; then
    comando...1
    comando...2
    comando...N
fi

-eq igual

-ne diferente

-gt maior

-ge maior ou igual

-lt menor

-le menor ou igual

-d se é um diretório

-e se existe

-z se é vazio

-f se contem texto.

-r se o arquivo possui permissão de leitura

-w se o arquivo possui permissão de escrita.

-x se o arquivo é executável.

Fonte: http://www.nacaolivre.com.br/shell-script/desvio-condicional-em-shell-script/

Unix - Special Variables

Previous tutorial warned about using certain nonalphanumeric characters in your variable names. This is because those characters are used in the names of special Unix variables. These variables are reserved for specific functions.

For example, the $ character represents the process ID number, or PID, of the current shell:

$echo $$

Above command would write PID of the current shell:

29949

The following table shows a number of special variables that you can use in your shell scripts:

Variable	Description
$0	The filename of the current script.
$n	These variables correspond to the arguments with which a script was invoked. Here n is a positive decimal number corresponding to the position of an argument (the first argument is $1, the second argument is $2, and so on).
$#	The number of arguments supplied to a script.
$*	All the arguments are double quoted. If a script receives two arguments, $* is equivalent to $1 $2.
$@	All the arguments are individually double quoted. If a script receives two arguments, $@ is equivalent to $1 $2.
$?	The exit status of the last command executed.
$$	The process number of the current shell. For shell scripts, this is the process ID under which they are executing.
$!	The process number of the last background command.

Command-Line Arguments:

The command-line arguments $1, $2, $3,...$9 are positional parameters, with $0 pointing to the actual command, program, shell script, or function and $1, $2, $3, ...$9 as the arguments to the command.

Following script uses various special variables related to command line:

#!/bin/sh

echo "File Name: $0"
echo "First Parameter : $1"
echo "First Parameter : $2"
echo "Quoted Values: $@"
echo "Quoted Values: $*"
echo "Total Number of Parameters : $#"

Here is a sample run for the above script:

$./test.sh Zara Ali
File Name : ./test.sh
First Parameter : Zara
Second Parameter : Ali
Quoted Values: Zara Ali
Quoted Values: Zara Ali
Total Number of Parameters : 2

Special Parameters $* and $@:

There are special parameters that allow accessing all of the command-line arguments at once. $* and $@ both will act the same unless they are enclosed in double quotes, "".

Both the parameter specifies all command-line arguments but the "$*" special parameter takes the entire list as one argument with spaces between and the "$@" special parameter takes the entire list and separates it into separate arguments.

We can write the shell script shown below to process an unknown number of command-line arguments with either the $* or $@ special parameters:

#!/bin/sh

for TOKEN in $*
do
   echo $TOKEN
done

There is one sample run for the above script:

$./test.sh Zara Ali 10 Years Old
Zara
Ali
10
Years
Old

Note: Here do...done is a kind of loop which we would cover in subsequent tutorial.

Exit Status:

The $? variable represents the exit status of the previous command.

Exit status is a numerical value returned by every command upon its completion. As a rule, most commands return an exit status of 0 if they were successful, and 1 if they were unsuccessful.

Some commands return additional exit statuses for particular reasons. For example, some commands differentiate between kinds of errors and will return various exit values depending on the specific type of failure.

Following is the example of successful command:

$./test.sh Zara Ali
File Name : ./test.sh
First Parameter : Zara
Second Parameter : Ali
Quoted Values: Zara Ali
Quoted Values: Zara Ali
Total Number of Parameters : 2
$echo $?
0
$

Fonte: tutorialspoint

MTU woes in IPsec tunnels and how you can fix it

Today I ran into a problem with IPsec Xauth PSK and the built-in Android VPN client (Android 4.1.2), resulting in some sites (such as www.yahoo.com) not loading through the VPN tunnel. Turns out I was dealing with MTU issues. When the Android VPN is started, it sets the MTU to 1500 on the tun0 interface:

$ ip link show tun0
33: tun0: <POINTOPOINT,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UNKNOWN qlen 500 link/none

Looking at the Android Source, it appears someone must have forgotten to take care of IPsec Xauth PSK. With PPTP and L2TP based VPNs, the MTU is reduced to 1400 (line 758 – 778).

In comparison:

• strongSwan Android client: MTU 1400
• OS X / iOS 7 built-in IPsec client: MTU 1280 (for what it’s worth, 1280 is also the minimum IPv6 packet size and thus the MTU minimum required to make IPv6 work)
• Windows 7 built-in IPsec client: MTU 1400
• Cisco VPN client: MTU 1300

Among the tested clients, only the connection through the Android VPN client was causing the issue with stalling websites. In a nutshell, I was able to fix it with the following on the VPN server:

$ iptables -t mangle -A FORWARD -o eth0 \
 -p tcp -m tcp --tcp-flags SYN,RST SYN \
 -m tcpmss --mss 1361:1536 \
 -j TCPMSS --set-mss 1360

$ echo 1 >/proc/sys/net/ipv4/ip_no_pmtu_disc

And here is why.

IP fragmentation – The original problem.

On the VPN server side, we have the interface set to a standard Ethernet MTU 1500. In the scenario with the Android client, the MTU along the entire path is 1500. This leaves room for up to 1460 bytes of data payload per packet (also referred to as the maximum segment size MSS).

Keep in mind that IPsec in tunnel mode adds an ESP header and an additional IP header for tunneling the packet (usually with an additional size of around 70-80 bytes). When a packet is nearly the size of the MTU and when you tack on this encapsulation overhead, it is likely to exceed the MTU of the outbound link.  That’s where IP fragmentation kicks in – which could lead to performance degradation of your VPN tunnel. Or worse…

Path MTU discovery (PMTUD). A failed solution.

To avoid IP fragmentation, many TCP/IP stacks have path MTU discovery (PMTUD) implemented. To tell you right away: It doesn’t work for me, and it’s not going to work for you either. PMTUD attempts to discover the largest IP datagram that may be sent without fragmentation through an IP path. Instead of fragmenting a too-large IP packet, the VPN server is told (through theDon’t Fragment (DF) flag in the IP header of the sender) to discard the packet and reply with an ICMP fragmentation required (type3, subtype 4) message.

Recap: The sender is the website that you try to load on your VPN client.

When the sender receives this ICMP packet, it learns to use a smaller MTU for packets sent to our VPN server. In theory. In reality, many websites (senders like www.yahoo.com) stupidly implement ICMP filters that break PMTUD functionality. And that’s where hell breaks loose.  The sender is expecting an acknowledgement for the original packet from our server, but since the packet was discarded, the acknowledgment never comes. Time goes by, then the sender repeats sending the too-large packet. The result? The VPN sender discards the packet, again, sends yet another ICMP message, and so on. Meanwhile our client on the other end of the VPN tunnel cannot tell what’s happening and is desperately waiting for some data. Everything appears to be stalled – a state which is also referred to as a black hole connection.

Because PMTUD doesn’t always work on the Internet, the use of it only makes sense in a site-to-site VPN, where basically one operator maintains the networks and is able to enable the forwarding of the “fragmentation required” ICMP (type 3, subtype 4) notifications in all firewalls in between.

MSS size reduction. A working solution.

So we can rule out PMTUD, but there is another way to assure that our VPN connection is working properly.

$ iptables -t mangle -A FORWARD -o eth0 \
 -p tcp -m tcp --tcp-flags SYN,RST SYN \
 -m tcpmss --mss 1361:1536 \
 -j TCPMSS --set-mss 1360

This iptables rule reduces the size of the allowed packet size by reducing the MSS of TCP SYN packets. The –set-mss value explicitly sets the MSS to 1360, which is a customary size for IPsec IPv4 interfaces. The –mss option is used to match only those MSS that are between 1361 and 1536 bytes (we don’t want to rewrite the MSS of a VPN client that uses a smaller MSS). The result in a tcpdump:

05:01:56.795798 IP 172.16.16.1.38695 > r2.ycpi.vip.ac4.yahoo.net.http: Flags [S], seq 2621580326, win 14600, options [mss 1460,sackOK,TS val 56614 ecr 0,nop,wscale 6], length 0
05:01:56.795865 IP vpn.zeitgeist.se.38695 > r2.ycpi.vip.ac4.yahoo.net.http: Flags [S], seq 2621580326, win 14600, options [mss 1360,sackOK,TS val 56614 ecr 0,nop,wscale 6], length 0
05:01:56.802695 IP r2.ycpi.vip.ac4.yahoo.net.http > vpn.zeitgeit.se.38695: Flags [S.], seq 3057551576, ack 2621580327, win 14480, options [mss 1460,sackOK,TS val 1410945796 ecr 56614,nop,wscale 8], length 0

In line 1, you see the request from our Android client through the tunnel to yahoo.com. Notice the MSS is 1460. In the second line, it is our VPN host initiating the TCP handshake with the external site. Only now  the MSS value is rewritten to 1360, thanks to our iptables rule. As a consequence, the TCP connection will use the lower MSS of the two end points, which is 1360. Voila!

You can go further and restrict the iptables rule to rewrite only those packets that are forwarded from our VPN client:

$ iptables -t mangle -A FORWARD -o eth0 \
 -p tcp -m tcp --tcp-flags SYN,RST SYN \
 -s 172.16.16.0/24 \
 -m tcpmss --mss 1361:1536 \
 -j TCPMSS --set-mss 1360

This assumes that the address pool of your virtual IPs is 172.16.16.0/24 (see rightsourceip in /etc/ipsec.conf).

There is also an option to determine the MSS size dynamically (“MSS clamping”, via the –clamp-mss-to-pmtu option), but it wouldn’t fix IPsec for clients that set their MTU too high (like in the Android example).

The MSS iptables rule doesn’t work with UDP applications. UDP is a connectionless protocol; hence there is no way to negotiate a MSS during the handshake. The only solution to guarantee that UDP works is to disable the Don’t Fragment (DF) bit in the IP header of the sender. This will allow our VPN server to fragment any UDP packet, if necessary. In Linux, you do it like this:

$ echo 1 >/proc/sys/net/ipv4/ip_no_pmtu_disc

The VPN server will fragment outgoing UDP packets that exceed the interface MTU, which may not be as great for performance and reliability reasons, but at least it doesn’t break the tunnel connection. Fortunately, most folks don’t use UDP for anything much greater than DNS.

Fonte: zeitgeist.se

INSTALANDO E CONFIGURANDO O VSFTPD – CENTOS

O VSFTP é um servidor de FTP muito fácil de configurar.

Começamos instalando ele.

# Na sua Shell rode:

yum install vsftpd -y

# Depois disto vamos no diretório dele para modificarmos o arquivo de configuração.

cd /etc/vsftpd

mv vsftpd.conf vsftpd.conf.BACKUP

vim vsftpd.conf

anonymous_enable=NO
local_enable=YES
write_enable=YES
local_umask=022
dirmessage_enable=YES
xferlog_enable=YES
connect_from_port_20=YES
xferlog_std_format=YES
ftpd_banner=Bem-Vindo ao FTP.
chroot_list_enable=YES
chroot_list_file=/etc/vsftpd/chroot_list
listen=YES
pam_service_name=vsftpd
userlist_enable=YES
tcp_wrappers=YES
xferlog_file=/var/log/vsftpd.log
pasv_enable=YES
pasv_min_port=12000
pasv_max_port=12100

# Note que no arquivo a cima, temos todos os parâmetros necessários para que o VSFTP funcione.

# Não esqueça de modificar as linhas: “ftpd_banner=Bem-Vindo ao FTP.” “chroot_list_file=/etc/vsftpd/chroot_list” “xferlog_file=/var/log/vsftpd.log”  conforme sua necessidade.

ftpd_banner=Bem-Vindo ao FTP. = Mensagem que será mostrada ao usuário quando ele se conectar no servidor.

chroot_list_file=/etc/vsftpd/chroot_list = Caminho do arquivo que contém os usuários liberados para acessar o FTP

xferlog_file=/var/log/vsftpd.log = Caminho do LOG do VSFTP

# Depois das modificações, basta Iniciarmos o VSFTP, criar o arquivo chroot_list e incluir o usuário no mesmo e criar o usuário FTP.

/etc/init.d/vsftpd start

touch /etc/vsftpd/chroot_list

adduser teste

vim /etc/vsftpd/chroot_list ( inclua aqui a linha “teste”, para informarmos ao VSFTP que o usuário será o teste )

Agora, você já tem um servidor FTP rodando.

Fonte: psyscrew

Linux Performance Measurements using vmstat

vmstat (virtual memory statistics) is a valuable monitoring utility, which also provides information about block IO and CPU activity in addition to memory.

vmstat Basics

vmstat provides a number of values and will typically be called using two numerical parameters.

Example: vmstat 1 5

• 1 -> the values will be re-measured and reported every second
• 5 -> the values will be reported five times and then the program will stop

The first line of the report will contain the average values since the last time the computer was rebooted. All other lines in the report will represent their respective current values. Vmstat does not need any special user rights. It can run as a normal user.

[user@fedora9 ~]$ vmstat 1 5
procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu------
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
 3  0      0  44712 110052 623096    0    0    30    28  217  888 13  3 83  1  0
 0  0      0  44408 110052 623096    0    0     0     0   88 1446 31  4 65  0  0
 0  0      0  44524 110052 623096    0    0     0     0   84  872 11  2 87  0  0
 0  0      0  44516 110052 623096    0    0     0     0  149 1429 18  5 77  0  0
 0  0      0  44524 110052 623096    0    0     0     0   60  431 14  1 85  0  0
[user@fedora9 ~]$

Meaning of the individual Values
(Source man vmstat):

Procs

• r: The number of processes waiting for run time.
• b: The number of processes in uninterruptible sleep.

Memory

• swpd: the amount of virtual memory used.
• free: the amount of idle memory.
• buff: the amount of memory used as buffers.
• cache: the amount of memory used as cache.
• inact: the amount of inactive memory. (-a option)
• active: the amount of active memory. (-a option)

Swap

• si: Amount of memory swapped in from disk (/s).
• so: Amount of memory swapped to disk (/s).

IO

• bi: Blocks received from a block device (blocks/s).
• bo: Blocks sent to a block device (blocks/s).

System

• in: The number of interrupts per second, including the clock.
• cs: The number of context switches per second.

CPU
These are percentages of total CPU time.

• us: Time spent running non-kernel code. (user time, including nice time)
• sy: Time spent running kernel code. (system time)
• id: Time spent idle. Prior to Linux 2.5.41, this includes IO-wait time.
• wa: Time spent waiting for IO. Prior to Linux 2.5.41, included in idle.
• st: Time stolen from a virtual machine. Prior to Linux 2.6.11, unknown.

Examples

CPU User Load Example
A standard audio file will be encode as an MP3 file by means of the lame encoder[1] in this example. This process is quite CPU intensive and also demonstrates the execution of vmstat in parallel with a user CPU time of 97%:

[user@fedora8 ~]$ vmstat 1 5
procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu------
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
 6  1      0 302380  16356 271852    0    0   561   568   80  590 43  7 43  7  0
 1  0      0 300892  16364 273256    0    0     0    52   79  274 97  3  0  0  0
 2  0      0 299544  16364 274532    0    0     0     0   78  372 97  3  0  0  0
 1  0      0 298292  16368 275780    0    0     0     0   53  255 97  3  0  0  0
 1  0      0 296820  16368 277192    0    0     0     0   77  377 97  3  0  0  0
[user@fedora8 ~]$

CPU System Load Example
In this example, a file will be filled with random content using dd.

[user@fedora9 ~]$ dd if=/dev/urandom of=500MBfile bs=1M count=500

For this, /dev/urandom[2] will supply random numbers, which will be generated by the kernel. This will lead to an increased load on the CPU (sy – system time). At the same time, the vmstat executing in parallel will indicate that between 93% and 97% of the CPU time is being used for the execution of kernel code (for the generation of random numbers, in this case).

[user@fedora9 ~]$ vmstat 1 5
procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu------
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
 2  0 402944  54000 161912 745324    5   14    54    59  221  867 13  3 82  2  0
 1  0 402944  53232 161916 748396    0    0     0     0   30  213  3 97  0  0  0
 1  0 402944  49752 161920 751452    0    0     0     0   28  290  4 96  0  0  0
 1  0 402944  45804 161924 755564    0    0     0     0   29  188  2 98  0  0  0
 1  0 402944  42568 161936 758608    0    0     0 17456  272  509  7 93  0  0  0
[user@fedora9 ~]$

The time for executing system calls[3][4][5] will be counted as system time (sy).

RAM Bottleneck (swapping) Example
In this example, many applications will be opened (including VirtualBox with a Windows guest system, among others). Almost all of the working memory will be used. Then, one more application (OpenOffice) will be started. The Linux kernel will then swap out several memory pages to the swap file on the hard disk, in order to get more RAM for OpenOffice. Swapping the memory pages to the swap file will be seen in the so (swap out - memory swapped to disk) column as vmstat executes in parallel.

[user@fedora8 ~]$ vmstat 1 5
procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu------
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
 3  1 244208  10312   1552  62636    4   23    98   249   44  304 28  3 68  1  0
 0  2 244920   6852   1844  67284    0  544  5248   544  236 1655  4  6  0 90  0
 1  2 256556   7468   1892  69356    0 3404  6048  3448  290 2604  5 12  0 83  0
 0  2 263832   8416   1952  71028    0 3788  2792  3788  140 2926 12 14  0 74  0
 0  3 274492   7704   1964  73064    0 4444  2812  5840  295 4201  8 22  0 69  0
[user@fedora8 ~]$


High IO Read Load Example

A large file (such as an ISO file) will be read and written to /dev/null using dd.

[user@fedora9 ~]$ dd if=bigfile.iso of=/dev/null bs=1M
Executed in parallel, vmstat will show the increased IO read load (the bi value).

[user@fedora9 ~]$ vmstat 1 5
procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu------
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
 3  1 465872  36132  82588 1018364    7   17    70   127  214  838 12  3 82  3  0
 0  1 465872  33796  82620 1021820    0    0 34592     0  357  781  6 10  0 84  0
 0  1 465872  36100  82656 1019660    0    0 34340     0  358  723  5  9  0 86  0
 0  1 465872  35744  82688 1020416    0    0 33312     0  345  892  8 11  0 81  0
 0  1 465872  35716  82572 1020948    0    0 34592     0  358  738  7  8  0 85  0
[user@fedora9 ~]$ 


High IO Write Load Example

In contrast with the previous example, dd will read from /dev/zero and write a file. The oflag=dsync will cause the data to be written immediately to the disk (and not merely stored in the page cache).

[user@fedora9 ~]$ dd if=/dev/zero of=500MBfile bs=1M count=500 oflag=dsync

Executed in parallel, vmstat will show the increased IO write load (the bo value).

[user@fedora9 ~]$ vmstat 1 5
procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu------
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
 1  1      0  35628  14700 1239164    0    0  1740   652  117  601 11  4 66 20  0
 0  1      0  34852  14896 1239788    0    0     0 23096  300  573  3 16  0 81  0
 0  1      0  32780  15080 1241304    0    0     4 21000  344  526  1 13  0 86  0
 0  1      0  36512  15244 1237256    0    0     0 19952  276  394  1 12  0 87  0
 0  1      0  35688  15412 1237180    0    0     0 18904  285  465  1 13  0 86  0
[user@fedora9 ~]$ 


CPU Waiting for IO Example

In the following example, an updatedb process is already running. The updatedb utility is part of mlocate. It examines the entire file system and accordingly creates the database for the locate command (by means of which file searches can be performed very quickly). Because updatedb reads all of the file names from the entire file system, the CPU must wait to get data from the IO system (the hard disk). For that reason, vmstat running in parallel will display large values for wa (waiting for IO):

[user@fedora9 ~]$ vmstat 1 5
procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu------
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
 2  1 403256 602848  17836 400356    5   15    50    50  207  861 13  3 83  1  0
 1  0 403256 601568  18892 400496    0    0  1048   364  337 1903  5  7  0 88  0
 0  1 403256 600816  19640 400568    0    0   748     0  259 1142  6  4  0 90  0
 0  1 403256 600300  20116 400800    0    0   476     0  196  630  8  5  0 87  0
 0  1 403256 599328  20792 400792    0    0   676     0  278 1401  7  5  0 88  0
[user@fedora9 ~]$

Additional vmstat Options

vmstat --help
[user@fedora9 ~]$ vmstat --help
usage: vmstat [-V] [-n] [delay [count]]
              -V prints version.
              -n causes the headers not to be reprinted regularly.
              -a print inactive/active page stats.
              -d prints disk statistics
              -D prints disk table
              -p prints disk partition statistics
              -s prints vm table
              -m prints slabinfo
              -S unit size
              delay is the delay between updates in seconds. 
              unit size k:1000 K:1024 m:1000000 M:1048576 (default is K)
              count is the number of updates.

[user@fedora9 ~]$

vmstat
[user@fedora9 ~]$ vmstat
procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu------
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
 2  0  14960  38016   6584 1069284    0    1   506    81  727 1373 12  4 81  3  0
[user@fedora9 ~]$

vmstat -V

[user@fedora9 ~]$ vmstat -V
procps version 3.2.7
[user@fedora9 ~]$

vmstat -a

[user@fedora9 ~]$ vmstat -a
procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu------
 r  b   swpd   free  inact active   si   so    bi    bo   in   cs us sy id wa st
 3  0  14960  38024 988284 461704    0    1   506    81  726 1372 12  4 81  3  0
[user@fedora9 ~]$

vmstat -d

[user@fedora9 ~]$ vmstat -d
disk- ------------reads------------ ------------writes----------- -----IO------
       total merged sectors      ms  total merged sectors      ms    cur    sec
ram0       0      0       0       0      0      0       0       0      0      0
ram1       0      0       0       0      0      0       0       0      0      0
ram2       0      0       0       0      0      0       0       0      0      0
ram3       0      0       0       0      0      0       0       0      0      0
ram4       0      0       0       0      0      0       0       0      0      0
ram5       0      0       0       0      0      0       0       0      0      0
ram6       0      0       0       0      0      0       0       0      0      0
ram7       0      0       0       0      0      0       0       0      0      0
ram8       0      0       0       0      0      0       0       0      0      0
ram9       0      0       0       0      0      0       0       0      0      0
ram10      0      0       0       0      0      0       0       0      0      0
ram11      0      0       0       0      0      0       0       0      0      0
ram12      0      0       0       0      0      0       0       0      0      0
ram13      0      0       0       0      0      0       0       0      0      0
ram14      0      0       0       0      0      0       0       0      0      0
ram15      0      0       0       0      0      0       0       0      0      0
sda   136909  31536 13893867 1197609  58190 219323 2233264 7688807      0    677
sda1   35703   6048 1326394  511477   6728  16136  182984  419232      0    222
sda2      85   1489    2935     653    141   3603   29952    5254      0      1
sda3  101111  23961 12564154  685330  51321 199584 2020328 7264321      0    512
sr0        0      0       0       0      0      0       0       0      0      0
fd0        0      0       0       0      0      0       0       0      0      0

[user@fedora9 ~]

vmstat -D

[user@fedora9 ~]$ vmstat -D
           22 disks 
            0 partitions 
       273820 total reads
        63034 merged reads
     27787446 read sectors
      2395193 milli reading
       116450 writes
       438666 merged writes
      4467248 written sectors
     15377932 milli writing
            0 inprogress IO
         1412 milli spent IO

vmstat -p

vmstat -p will not work under Fedora: https://bugzilla.redhat.com/show_bug.cgi?id=485246. The following report comes from an Ubuntu 9.10 system.

user@ubuntu-9-10:~$ vmstat -p /dev/sda9
sda9          reads   read sectors  writes    requested writes
               23420     411365      24464     530801

user@ubuntu-9-10:~$

vmstat -s

[user@fedora9 ~]$ vmstat -s
      1553972  total memory
      1516180  used memory
       461892  active memory
       988304  inactive memory
        37792  free memory
         6644  buffer memory
      1069388  swap cache
      1052248  total swap
        14960  used swap
      1037288  free swap
       161467 non-nice user cpu ticks
         7586 nice user cpu ticks
        46310 system cpu ticks
      1108919 idle cpu ticks
        46832 IO-wait cpu ticks
         2694 IRQ cpu ticks
         2452 softirq cpu ticks
            0 stolen cpu ticks
      6947021 pages paged in
      1116896 pages paged out
          183 pages swapped in
         3744 pages swapped out
      9985406 interrupts
     18852586 CPU context switches
   1239004323 boot time
        15072 forks

[user@fedora9 ~]$

vmstat -m

[user@fedora9 ~]$ vmstat -m
Cache                       Num  Total   Size  Pages
fuse_request                 11     11    368     11
fuse_inode                    9      9    448      9
rpc_inode_cache               8      8    512      8
nf_conntrack_expect           0      0    168     24
nf_conntrack                 26     80    248     16
dm_uevent                     0      0   2464      3
UDPv6                        22     22    704     11
TCPv6                         6      6   1344      6
kmalloc_dma-512               8      8    512      8
sgpool-128                   12     12   2048      4
scsi_io_context               0      0    104     39
ext3_inode_cache           6822   8360    496      8
ext3_xattr                   85     85     48     85
journal_handle              170    170     24    170
journal_head                 76    219     56     73
revoke_record               256    256     16    256
flow_cache                    0      0     80     51
bsg_cmd                       0      0    288     14
mqueue_inode_cache            7      7    576      7
isofs_inode_cache             0      0    376     10
hugetlbfs_inode_cache        11     11    344     11
dquot                         0      0    128     32
shmem_inode_cache          1058   1071    448      9
xfrm_dst_cache                0      0    320     12
UDP                          19     21    576      7
TCP                          17     24   1216      6
blkdev_queue                 21     21   1080      7
biovec-256                    2      2   3072      2
biovec-128                    5      5   1536      5
biovec-64                     7     10    768      5
sock_inode_cache            619    650    384     10
file_lock_cache              39     39    104     39
Acpi-Operand               2935   2958     40    102
Acpi-Namespace             1700   1700     24    170
Cache                       Num  Total   Size  Pages
taskstats                    25     26    312     13
proc_inode_cache            233    242    360     11
sigqueue                     28     28    144     28
radix_tree_node            7888   8606    296     13
bdev_cache                   24     24    512      8
inode_cache                 370    462    344     11
dentry                     6592  15390    136     30
names_cache                   2      2   4096      2
avc_node                     73     73     56     73
selinux_inode_security     9888  10030     48     85
idr_layer_cache             627    644    144     28
buffer_head                2308   2688     64     64
mm_struct                   659    693    448      9
vm_area_struct            11110  11592     88     46
files_cache                 115    130    384     10
sighand_cache               141    150   1344      6
task_struct                 246    248   3696      2
anon_vma                   4778   5120     16    256
kmalloc-4096                 95    112   4096      8
kmalloc-2048                272    304   2048     16
kmalloc-1024                518    524   1024      4
kmalloc-512                 764    888    512      8
kmalloc-256                 198    208    256     16
kmalloc-128                 629    832    128     32
kmalloc-64                 4322   5568     64     64
kmalloc-32                 1554   1664     32    128
kmalloc-16                 2644   3584     16    256
kmalloc-8                  3561   3584      8    512
kmalloc-192                6349   6930    192     21
kmalloc-96                  885   1176     96     42
[user@fedora9 ~]$ 


References
http://lame.sourceforge.net/
http://en.wikipedia.org/wiki//dev/random
http://en.wikipedia.org/wiki/System_call
http://www.softpanorama.org/Internals/unix_system_calls.shtml
http://www.ibm.com/developerworks/linux/library/l-system-calls/