This article is part of the article series "Unix Utilities You Should Know About."
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Unix UtilitiesThis is the second post in the article series about Unix utilities that you should know about. In this post I will introduce you to the netcat tool or simply nc.

Netcat is often referred to as a "Swiss Army knife" utility, and for a good reason. Just like the multi-function usefulness of the venerable Swiss Army pocket knife, netcat's functionality is as helpful. Some of its features include port scanning, transferring files, port listening and it can be used a backdoor.

In 2006 netcat was ranked #4 in "Top 100 Network Security Tools" survey, so it's definitely a tool to know.

See the first post on pipe viewer for the introduction to this article series. If you feel like you are interested in this stuff, I suggest that you subscribe to my rss feed to receive my future posts automatically.

How to use nc?

Let's start with a few very simple examples and build up on those.

If you remember, I said that netcat was a Swiss Army knife. What would a Swiss Army knife be if it also wasn't a regular knife, right? That's why netcat can be used as a replacement of telnet:

$ nc www.google.com 80

It's actually much more handy than the regular telnet because you can terminate the connection at any time with ctrl+c, and it handles binary data as regular data (no escape codes, nothing).

You may add "-v" parameter for more verboseness, and two -v's (-vv) to get statistics of how many bytes were transmitted during the connection.

Netcat can also be used as a server itself. If you start it as following, it will listen on port 12345 (on all interfaces):

$ nc -l -p 12345

If you now connect to port 12345 on that host, everything you type will be sent to the other party, which leads us to using netcat as a chat server. Start the server on one computer:

# On a computer A with IP 10.10.10.10
$ nc -l -p 12345

And connect to it from another:

# On computer B
$ nc 10.10.10.10 12345

Now both parties can chat!

Talking of which, the chat can be turned to make two processes talk to each other, thus making nc do I/O over network! For example, you can send the whole directory from one computer to another by piping tar to nc on the first computer, and redirecting output to another tar process on the second.

Suppose you want to send files in /data from computer A with IP 192.168.1.10 to computer B (with any IP). It's as simple as this:

# On computer A with IP 192.168.1.10
$ tar -cf - /data | nc -l -p 6666

# On computer B
$ nc 192.168.1.10 6666 | tar -xf -

Don't forget to combine the pipeline with pipe viewer from previous article in this series to get statistics on how fast the transfer is going!

A single file can be sent even easier:

# On computer A with IP 192.168.1.10
$ cat file | nc -l -p 6666

# On computer B
$ nc 192.168.1.10 6666 > file

You may even copy and restore the whole disk with nc:

# On computer A with IP 192.168.1.10
$ cat /dev/hdb | nc -l -p 6666

# On computer B
$ nc 192.168.1.10 6666 > /dev/hdb

Note: It turns out that "-l" can't be used together with "-p" on a Mac! The solution is to replace "-l -p 6666" with just "-l 6666". Like this:

$ nc -l 6666

# nc now listens on port 6666 on a Mac computer

An uncommon use of netcat is port scanning. Netcat is not the best tool for this job, but it does it ok (the best tool is nmap):

$ nc -v -n -z -w 1 192.168.1.2 1-1000 
(UNKNOWN) [192.168.1.2] 445 (microsoft-ds) open
(UNKNOWN) [192.168.1.2] 139 (netbios-ssn) open
(UNKNOWN) [192.168.1.2] 111 (sunrpc) open
(UNKNOWN) [192.168.1.2] 80 (www) open
(UNKNOWN) [192.168.1.2] 25 (smtp) : Connection timed out
(UNKNOWN) [192.168.1.2] 22 (ssh) open

The "-n" parameter here prevents DNS lookup, "-z" makes nc not to receive any data from the server, and "-w 1" makes the connection timeout after 1 second of inactivity.

Another uncommon behavior is using netcat as a proxy. Both ports and hosts can be redirected. Look at this example:

$ nc -l -p 12345 | nc www.google.com 80

This starts a nc server on port 12345 and all the connections get redirected to google.com:80. If you now connect to that computer on port 12345 and do a request, you will find that no data gets sent back. That's correct, because we did not set up a bidirectional pipe. If you add another pipe, you can get the data back on another port:

$ nc -l -p 12345 | nc www.google.com 80 | nc -l -p 12346

After you have sent the request on port 12345, connect on port 12346 to get the data.

Probably the most powerful netcat's feature is making any process a server:

$ nc -l -p 12345 -e /bin/bash

The "-e" option spawns the executable with it's input and output redirected via network socket. If you now connect to the host on port 12345, you may use bash:

$ nc localhost 12345
ls -las
total 4288
   4 drwxr-xr-x 15 pkrumins users    4096 2009-02-17 07:47 .
   4 drwxr-xr-x  4 pkrumins users    4096 2009-01-18 21:22 ..
   8 -rw-------  1 pkrumins users    8192 2009-02-16 19:30 .bash_history
   4 -rw-r--r--  1 pkrumins users     220 2009-01-18 21:04 .bash_logout
   ...

The consequences are that nc is a popular hacker tool as it is so easy to create a backdoor on any computer. On a Linux computer you may spawn /bin/bash and on a Windows computer cmd.exe to have total control over it.

That's everything I can think of. Do you know any other netcat uses that I did not include?

How to install nc?

If you're on Debian or Debian based system such as Ubuntu do the following:

$ sudo aptitude install netcat

If you're on Fedora or Fedora based system such as CentOS do:

$ sudo yum install netcat

If you're on Slackware, FreeBSD, NetBSD, Solaris or Mac, download the source code of nc and just:

$ tar -zxf nc-version.tar.gz
$ cd nc-version
$ ./configure && sudo make install

Another way to do it on Mac, if you have MacPorts is:

$ sudo port install netcat

On Slackware you can actually install it as a package from n/ package directory:

$ sudo installpkg nc-1.10-i386-1.tgz

If you're on Windows, download the Windoze port of it from securityfocus.

The manual of the utility can be found here man nc.

Have fun netcatting, and until next time!

This article is part of the article series "Awk One-Liners Explained."
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awk programming one-liners explainedThis is an update post on my three-part article Famous Awk One-Liners Explained.

I received an email from Eric Pement (the original author of Awk one-liners) and he said that there was a new version of awk1line.txt file available. I did a diff and found that there were seven new one-liners in it!

The new file has two new sections "String Creation" and "Array Creation" and it updates "Selective Printing of Certain Lines" section. I'll explain the new one-liners in this article.

Here is the latest version of awk1line.txt: awk1line-new.txt.

The original Eric Pement's Awk one-liner collection consists of five sections, and I explained them in my previous three articles:

Awesome news: I have written an e-book based on this article series. Check it out:

Okay, let's roll with the new one-liners:

String Creation

1. Create a string of a specific length (generate a string of x's of length 513).

awk 'BEGIN { while (a++<513) s=s "x"; print s }'

This one-liner uses the "BEGIN { }" special block that gets executed before anything else in an Awk program. In this block a while loop appends character "x" to variable "s" 513 times. After it has looped, the "s" variable gets printed out. As this Awk program does not have a body, it quits after executing the BEGIN block.

This one-liner printed the 513 x's out, but you could have used it for anything you wish in BEGIN, main program or END blocks.

Unfortunately this is not the most effective way to do it. It's a linear time solution. My friend waldner (who, by the way, wrote a guest post on 10 Awk Tips, Tricks and Pitfalls) showed me a solution that's logarithmic time (based on idea of recursive squaring):

function rep(str, num,     remain, result) {
    if (num < 2) {
        remain = (num == 1)
    } else {
        remain = (num % 2 == 1)
        result = rep(str, (num - remain) / 2)
    }
    return result result (remain ? str  : "")
}

This function can be used as following:

awk 'BEGIN { s = rep("x", 513) }'

2. Insert a string of specific length at a certain character position (insert 49 x's after 6th char).

gawk --re-interval 'BEGIN{ while(a++<49) s=s "x" }; { sub(/^.{6}/,"&" s) }; 1'

This one-liner works only with Gnu Awk, because it uses the interval expression ".{6}" in the Awk program's body. Interval expressions were not traditionally available in awk, that's why you have to use "--re-interval" option to enable them.

For those that do not know what interval expressions are, they are regular expressions that match a certain number of characters. For example, ".{6}" matches any six characters (the any char is specified by the dot "."). An interval expression "b{2,4}" matches at least two, but not more than four "b" characters. To match words, you have to give them higher precedence - "(foo){4}" matches "foo" repeated four times - "foofoofoofoo".

The one-liner starts the same way as the previous - it creates a 49 character string "s" in the BEGIN block. Next, for each line of the input, it calls sub() function that replaces the first 6 characters with themselves and "s" appended. The "&" in the sub() function means the matched part of regular expression. The '"&" s' means matched part of regex and contents of variable "s". The "1" at the end of whole Awk one-liner prints out the modified line (it's syntactic sugar for just "print" (that itself is syntactic sugar for "print $0")).

The same can be achieved with normal standard Awk:

awk 'BEGIN{ while(a++<49) s=s "x" }; { sub(/^....../,"&" s) }; 1

Here we just match six chars "......" at the beginning of line, and replace them with themselves + contents of variable "s".

It may get troublesome to insert a string at 29th position for example... You'd have to go tapping "." twenty-nine times ".............................". Better use Gnu Awk then and write ".{29}".

Once again, my friend waldner corrected me and pointed to Awk Feature Comparsion chart. The chart suggests that the original one-liner with ".{6}" would also work with POSIX awk, Busybox awk, and Solaris awk.

Array Creation

3. Create an array from string.

split("Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec", month, " ")

This is not a one-liner per se but a technique to create an array from a string. The split(Str, Arr, Regex) function is used do that. It splits string Str into fields by regular expression Regex and puts the fields in array Arr. The fields are placed in Arr[1], Arr[2], ..., Arr[N]. The split() function itself returns the number of fields the string was split into.

In this piece of code the Regex is simply space character " ", the array is month and string is "Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec". After the split, month[1] is "Jan", month[2] is "Feb", ..., month[12] is "Dec".

4. Create an array named "mdigit", indexed by strings.

for (i=1; i<=12; i++) mdigit[month[i]] = i

This is another array creation technique and not a real one-liner. This technique creates a reverse lookup array. Remember from the previous "one-liner" that month[1] was "Jan", ..., month[12] was "Dec". Now we want to the reverse lookup and find the number for each month. To do that we create a reverse lookup array "mdigit", such that mdigit["Jan"] = 1, ..., mdigit["Dec"] = 12.

It's really trivial, we loop over month[1], month[2], ..., month[12] and set mdigit[month[i]] to i. This way mdigit["Jan"] = 1, etc.

Selective Printing of Certain Lines

5. Print all lines where 5th field is equal to "abc123".

awk '$5 == "abc123"'

This one-liner uses idiomatic Awk - if the given expression is true, Awk prints out the line. The fifth field is referenced by "$5" and it's checked to be equal to "abc123". If it is, the expression is true and the line gets printed.

Unwinding this idiom, this one-liner is really equal to:

awk '{ if ($5 == "abc123") { print $0 } }'

6. Print any line where field #5 is not equal to "abc123".

awk '$5 != "abc123"'

This is exactly the same as previous one-liner, except it negates the comparison. If the fifth field "$5" is not equal to "abc123", then print it.

Unwinding it, it's equal to:

awk '{ if ($5 != "abc123") { print $0 } }'

Another way is to literally negate the whole previous one-liner:

awk '!($5 == "abc123")'

7. Print all lines whose 7th field matches a regular expression.

awk '$7  ~ /^[a-f]/'

This is also idiomatic Awk. It uses "~" operator to test if the seventh "$7" field matches a regular expression "^[a-f]". This regular expression means "all lines that start with a lower-case letter a, b, c, d, e, or f".

awk '$7 !~ /^[a-f]/'

This one-liner matches negates the previous one and prints all lines that do not start with a lower-case letter a, b, c, d, e, and f.

Another way to write the same is:

awk '$7 ~ /^[^a-f]/'

Here we negated the group of letters [a-f] by adding "^" in the group. That's a regex trick to know.

Awk one-liners explained e-book

I have written my first e-book called "Awk One-Liners Explained". I improved the explanations of the one-liners in this article series, added new one-liners and added three new chapters - introduction to awk one-liners, summary of awk special variables and idiomatic awk. Please take a look:

Have Fun!

Have fun with these Awk oneliners!

If you haven't already, I recommend that you download my Awk cheat-cheet, read the "10 Awk Tips, Tricks and Pitfalls" article, and study the source code of my YouTube Video Downloader, written entirely in Gnu Awk.

This article is part of the article series "Musical Geek Friday."
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Don’t Copy That FloppyI have found some new geek songs to post on my Musical Geek Friday. This week it's a song called Hax That Fsck. It's a hip-hop/rap song about a hacker getting owned by FBI and his adventures in hacking Gibson and CIA.

The song is written by Finnish band called "Leech Axss". This is their second geek song that I have posted on Musical Geek Friday. See "Leech Access is Coming at You".

I had problems with understanding some parts of the song. I put "(???)" in the lyrics where I was not sure what was being said. I'd appreciate if someone helped me figure it out the correct lyrics!

The song is strongly NSFW, be sure to put your headphones on before listening at work.

[audio:http://www.catonmat.net/download/leech_axss-hax_that_fuck.mp3]

Download this song: hax that fsck (musical geek friday #17)
Downloaded: 70715 times

Download lyrics: hax that fsck lyrics (musical geek friday #17)
Downloaded: 4535 times

Here is the lyrics (I censored the explicit language, see the 'download lyrics' link above for uncensored version):

Hax that f**k, move that box
Exploit a hole in a FireFox
Haxing is about breaking in, not fame
Whoever you be haxing is all the same

Crack that code, buffer overflow
Alt-F4 makes a lamer go
Hax that Gibson and CIA
Sell your soul to the zero da-aa-ay

As you well know, I net sex with duty creatures (???)
I now have sex with the federal agents
You bruteforce the password of gay.com
Knock, knock, it's the feds and the bubba is on

Right to remain silent like my box in ice
Perfect source code, never write it twice
Better go figure it out before you talk to a fed
It's a feeling very close to a blue screen of death

A monkey Steve Jobs intringing with Bill Gates
That ain't gonna tway with the fscking absura blades (????)
Apple in my eye and a panther in my tank
I bought an itunes that are like tri-hand ****

Still in the game but before I went away
Nerdies want my wishes and they want my zero days
But behave you geeks, and I won't go latest patch
The one that cycle is Christina Aguilera snatch

Hax that f**k, move that box
Exploit a hole in the FireFox
Haxing is about breaking in, not fame
Whoever you be haxing is all the same

Crack that code, buffer overflow
Alt-F4 makes a lamer go
Hax that Gibson and CIA
Sell your soul to the zero da-aa-ay

I read b0w and b0g
I sport AMD and fscking RISC
I am not like you, I never disrespect my box
Points to stolen motherf*****g Mozilla leanfox

What's under the hood, I've got future of jobs
Thousand mp3s in the court
Drop it like it's hot, drop it like it's hot, drop it like it's hot
Check my benchmark, you skinny retard

[Hshhha] loves a key generator
If it's not 0day, don't seed it later
I met my share of lamers, I've got some spleen
Zero entropy is like Commander Keen

I've been in hax of yours and to haxifice
I've seen in the eyes which drugsterize (???)
I'm haxing my way out of the paper bag
Authenticating g in my f*****g ... (???)

Hax that f**k, move that box
Exploit a hole in the FireFox
Haxing is about breaking in, not fame
Whoever you be haxing is all the same

Crack that code, buffer overflow
Alt-F4 makes a lamer go
Hack that Gibbson and CIA
Sell your soul to the zero da-aa-ay

Hax that fsck, move that box
Exploit a hole in the FireFox
Haxing is about breaking in, not fame
Whoever you be haxing is all the same

Crack that code, buffer overflow
Alt-F4 makes a lamer go
Hax that Gibson and CIA
Sell your soul to the zero da-aa-ay

Download "Hax That Fsck" Song

Download this song: hax that fsck (musical geek friday #17)
Downloaded: 70715 times

Download lyrics: hax that fsck lyrics (musical geek friday #17)
Downloaded: 4535 times

Click to listen:
[audio:http://www.catonmat.net/download/leech_axss-hax_that_fuck.mp3]

Have fun and until next geeky Friday! :)

This article is part of the article series "Vim Plugins You Should Know About."
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Vim Plugins, surround.vimThis is the third post in the article series "Vim Plugins You Should Know About". This time I am going to introduce you to a plugin called "matchit.vim".

If you are intrigued by this topic, I suggest that you subscribe to my posts! For the introduction and first post in this article series, follow this link - Vim Plugins You Should Know About, Part I: surround.vim. Part II is here: repeat.vim.

Matchit extends the existing functionality of "%" key (percent key). I'll first briefly remind you what the original "%" does and then explain how matchit.vim enhances it.

The original "%" key allows you to jump between various pairs of characters and some programming constructs. For example, it jumps between pairs of parenthesis ( )'s, { }'s, [ ]'s. It also jumps between opening and closing tags of C style comments /* and */. And it's smart enough to jump between C preprocessor directives - from #if to #endif and match #elif or #else in between.

Here is an example. Suppose you have this code and you press "%", the cursor jumps between { and } parens:

matchit vim plugin example

Matchit.vim extends this functionality. It's written by Benji Fisher and it adds support to cycle between if, else if, else, endif keywords in various programming languages. Another improvement is the ability to find pairs of HTML tags, such as <p> ... </p>. Another handy mapping is "g%" that does "%" in opposite direction (goes from endif to else to else if to if). The plugin also includes several other mappings like "]%", "[%" and "a%" but I could not figure out how to effectively use them in real life code, so I don't use them at all.

Here is another example. Suppose you are editing this HTML and you quickly want to go to the corresponding closing tag of <body>. Just press "%":

matchit vim html example

Overall it's a great plugin to have in your inventory!

How to install matchit.vim?

Matchit.vim has been included in vim since version 6.0. However there are newer versions of the script available with bug fixes and enhancements.

To get the latest version:

  • 1. Download matchit.zip.
  • 2. Extract matchit.zip to ~/.vim (on Unix/Linux) or ~\vimfiles (on Windows).
  • 3. Run :helptags ~/.vim/doc (on Unix/Linux) or :helptags ~/vimfiles/doc (on Windows) to rebuild the tags file (so that you can read :help %, :help g%, etc.)
  • 4. Restart Vim or source matchit.vim with ":so ~/.vim/plugin/matchit.vim" on Unix or ":so ~/vimfiles/plugin/matchit.vim" on Windows).
  • 5. Use '%' to find corresponding

For Python programmers: Turns out the original matchit.vim plugin does not match if / elif / else. Benji extended matchit.vim itself and created "python_matchit.vim". This extension allows us to use the "%" key to cycle through if/elif/else, try/except/catch, for/continue/break, and while/continue/break structures. The script also defines g% to cycle in the opposite direction, and it defines two other motions, [% and ]%, go to the start and end of the current block, respectively.

How to install python_matchit.vim?

Python_matchit.vim is a filetype plugin. It has to be installed in "ftplugin" directory. Follow these steps to get it installed:

  • 1. Download python_matchit.vim.
  • 2. Put it in ~/.vim/ftplugin (on Unix/Linux) or ~\vimfiles\ftplugin (on Windows).
  • 3. Restart Vim or source matchit.vim with ":so ~/.vim/ftplugin/python_matchit.vim" on Unix or ":so ~/vimfiles/ftplugin/python_matchit.vim" on Windows).

The same steps can be taken to install matchit for Ruby.

Have Fun!

Happy matching with matchit.vim!

This article is part of the article series "Unix Utilities You Should Know About."
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Unix UtilitiesHi all. I'm starting yet another article series here. This one is going to be about Unix utilities that you should know about. The articles will discuss one Unix program at a time. I'll try to write a good introduction to the tool and give as many examples as I can think of.

Before I start, I want to clarify one thing - Why am I starting so many article series? The answer is that I want to write about many topics simultaneously and switch between them as I feel inspired.

The first post in this series is going to be about not so well known Unix program called Pipe Viewer or pv for short. Pipe viewer is a terminal-based tool for monitoring the progress of data through a pipeline. It can be inserted into any normal pipeline between two processes to give a visual indication of how quickly data is passing through, how long it has taken, how near to completion it is, and an estimate of how long it will be until completion.

Pipe viewer is written by Andrew Wood, an experienced Unix sysadmin. The homepage of pv utility is here: pv utility.

If you feel like you are interested in this stuff, I suggest that you subscribe to my rss feed to receive my future posts automatically.

How to use pv?

Ok, let's start with some really easy examples and progress to more complicated ones.

Suppose that you had a file "access.log" that is a few gigabytes in size and contains web logs. You want to compress it into a smaller file, let's say a gunzip archive (.gz). The obvious way would be to do:

$ gzip -c access.log > access.log.gz

As the file is so huge (several gigabytes), you have no idea how long to wait. Will it finish soon? Or will it take another 30 mins?

By using pv you can precisely time how long it will take. Take a look at doing the same through pv:

$ pv access.log | gzip > access.log.gz
611MB 0:00:11 [58.3MB/s] [=>      ] 15% ETA 0:00:59

Pipe viewer acts as "cat" here, except it also adds a progress bar. We can see that gzip processed 611MB of data in 11 seconds. It has processed 15% of all data and it will take 59 more seconds to finish.

You may stick several pv processes in between. For example, you can time how fast the data is being read from the disk and how much data is gzip outputting:

$ pv -cN source access.log | gzip | pv -cN gzip > access.log.gz
source:  760MB 0:00:15 [37.4MB/s] [=>     ] 19% ETA 0:01:02
  gzip: 34.5MB 0:00:15 [1.74MB/s] [  <=>  ]

Here we specified the "-N" parameter to pv to create a named stream. The "-c" parameter makes sure the output is not garbaged by one pv process writing over the other.

This example shows that "access.log" file is being read at a speed of 37.4MB/s but gzip is writing data at only 1.74MB/s. We can immediately calculate the compression rate. It's 37.4/1.74 = 21x!

Notice how the gzip does not include how much data is left or how fast it will finish. It's because the pv process after gzip has no idea how much data gzip will produce (it's just outputting compressed data from input stream). The first pv process, however, knows how much data is left, because it's reading it.

Another similar example would be to pack the whole directory of files into a compressed tarball:

$ tar -czf - . | pv > out.tgz
 117MB 0:00:55 [2.7MB/s] [>         ]

In this example pv shows just the output rate of "tar -czf" command. Not very interesting and it does not provide information about how much data is left. We need to provide the total size of data we are tarring to pv, it's done this way:

$ tar -cf - . | pv -s $(du -sb . | awk '{print $1}') | gzip > out.tgz
 253MB 0:00:05 [46.7MB/s] [>     ]  1% ETA 0:04:49

What happens here is we tell tar to create "-c" an archive of all files in current dir "." (recursively) and output the data to stdout "-f -". Next we specify the size "-s" to pv of all files in current dir. The "du -sb . | awk '{print $1}'" returns number of bytes in current dir, and it gets fed as "-s" parameter to pv. Next we gzip the whole content and output the result to out.tgz file. This way "pv" knows how much data is still left to be processed and shows us that it will take yet another 4 mins 49 secs to finish.

Another fine example is copying large amounts of data over network by using help of "nc" utility that I will write about some other time.

Suppose you have two computers A and B. You want to transfer a directory from A to B very quickly. The fastest way is to use tar and nc, and time the operation with pv.

# on computer A, with IP address 192.168.1.100
$ tar -cf - /path/to/dir | pv | nc -l -p 6666 -q 5
# on computer B
$ nc 192.168.1.100 6666 | pv | tar -xf -

That's it. All the files in /path/to/dir on computer A will get transferred to computer B, and you'll be able to see how fast the operation is going.

If you want the progress bar, you have to do the "pv -s $(...)" trick from the previous example (only on computer A).

Another funny example is by my blog reader alexandru. He shows how to time how fast the computer reads from /dev/zero:

$ pv /dev/zero > /dev/null
 157GB 0:00:38 [4,17GB/s]

That's about it. I hope you enjoyed my examples and learned something new. I love explaining things and teaching! :)

How to install pv?

If you're on Debian or Debian based system such as Ubuntu do the following:

$ sudo aptitude install pv

If you're on Fedora or Fedora based system such as CentOS do:

$ sudo yum install pv

If you're on Slackware, go to pv homepage, download the pv-version.tar.gz archive and do:

$ tar -zxf pv-version.tar.gz
$ cd pv-version
$ ./configure && sudo make install

If you're a Mac user:

$ sudo port install pv

If you're OpenSolaris user:

$ pfexec pkg install pv

If you're a Windows user on Cygwin:

$ ./configure
$ export DESTDIR=/cygdrive/c/cygwin
$ make
$ make install

The manual of the utility can be found here man pv.

Have fun measuring your pipes with pv, and until next time!